It all depends on what you think you would be more comfortable with as each class has its own advantages. Do you want to be able to solo and be able to just look after yourself? Or would you like to be able to better assist friends you make along the way? Or do you want to deal high dps or high dmg aoe in order to lvl quicker? Some classes regardless of build are always popular as they're in high demand for pt so their easy to find a pt for to lvl and to do mq.
I'd say vit or agi build would be best for you to start with as both offer a good deal in terms of survivability as that would give you a bit more freedom to better enjoy the iruna experience without just getting 1 hit killed all the time.
For new players, I would probably suggest for vit build, either beast knight or paladin. Both these classes up to 3rd teir would be pretty well on par in terms of build and gear, well there's a number of different builds with different gear sets for beast knight, but for vit/dex build which offers best survival they are about the same.
After changing to 3rd teir class tho...I'd prob say beast knight out of the 2 tbh just because at class change at 120 OT gets passive skill bite which basically leeches HP from the mobs as you atk, this passive skill would be more effective with crt to make it trigger more regularly, but with that vit build, you can kind of afford to not have it all the time when you have that tankyness from vit. Idk which gear would be best for this build for BK after skill change but as you might've seen,
mokie has done up a thread outlining all different builds for it and I think some of the equip would be mentioned there.
For paladin, is great for pt because it gets heal at 120 so is really good in terms of support, it gets Gloria also which is great for extra atk on dark element mobs...it's other skills come a bit later tho. The good point for pal tho is equip is, in comparison to other classes, relatively affordable.
I'd definitely say have a go at monk with their agi/crt build coz they look really fun lol and that agi makes for high survivability coz where with vit you can take the hits, with agi you just avoid them (except some crt hits >_< ) and at later lvls, it's dps depending on the build, is right up with with the highest dealing dps(damage per second)hunter classes. only thing with monk tho is it's gear is reeeaaally expensive.
If you want something that means survivable in terms of being able to find a pt more easily to lvl I'd say...pretty well anything branching off mage class(or 2 of the special classes which I'll describe a bit further down) at the start as both enchanters and high wizards have MP heal which every1 loves to have them in pt for, and then you have Bishop also which depending on build, can be simply support and just sit back and heal in the earlier lvls and have some kickass moves for later on, or can be really tanky tho that means forfeiting being able to spamsaid kickass moves for a good deal longer than would otherwise be the case. Idk much about gear or builds for these classes, but each has its own advantages. I'd say tho, for a beginner to more comfortably find their way around, for wiz I'd prob say the int bit dex build as that offers a bit more tankieness and solo capability later on and for enchanter I'd say look up their m blade spammer build as this is really good for survivability at later lvls.
For Bishop, you could either go for survival and throw some vit in as you raise you int or a bit for after you max your int, tho like I said before this would mean having longer to wait to be able to spam the skill nemesis that you get at 180 which deals some really groovy dmg to mobs but you need to at least have maxed dex to be able to spam this skill which otherwise has I think it's a 5sec skill delay. Otherwise, like ench and hw for their MP heal, Bishop is a great support class and is really popular for pt and even if it lacks that tankieness, as long as you find the right ppl at the start as you grind for lvls, you can pt with them on mq also and just basically chill on the edge of the map and just keep an eye on their HP to heal as needed.
I must of course give a mention to the hunter type classes assassin and sniper here as they both have incredible advantages in terms of buffs they can give to ward off and they also have some, or should I say the highest dps out of any class in game, tho idk about suggesting to a new player these classes as because of...say certain myths many are fed about ninja, these hunter type classes are sadly very over shadowed and overlooked by the greater and more ignorant population(being ninjas) of iruna which thereby can make it difficult to find a pt.
Then you have your special classes which are as you may have read, those you can change to at lvl 100. I would suggest out of these special classes either minsteral or servant.
For minsteral, there's not a terrible lot I can say as I've never really looked into it much before, but it is I do know, a class that can basically do anything it wants depending on how you build it. The big winner for minsteral is because they have so many really good pt buffs that suit all classes, they are easy these days 1 of the classes that are most in demand for pt.
Then you have servant which is only a really new class but has many benefits that would put it on or near to pat with Bishop. Only thing for this class tho is it's skills and potential are not truly known or understood as yet so my suggestion if you decide you like the look of this 1 and as its basically the same build as Bishop would be, focus on hitting the grind spots and hit them hard, make sure to pt with as many people as possible in order to scout out potential recruits to your friend list to continue to pt with for grind and also to team up for mq with. If you don't have a good list of people that are regularly in game that you can pick from to pt with as needed, as I said before its not a class that is widely known or appreciated as yet so finding pt for mq could prove difficult.
Then...*sighs* I should mention this class if only as not to be labelled a hater (I am)
Ninja...there's a few different builds for this class, but the most common(emphasis on this word) build is agi/crt which offers probably the best survivability in game, their only real weakness being ailments and stun (stun is every1s enemy but it's really a ninja killer lol) and right through from 100-200 it's probably the cheapest to equip in game on the generic claw build where ganai(an xtal that gives -30%HP which ninja need to be able to clone which costs...ugh price seems to keep going up while there are still as many ppl farming it as ever before, I've seen recently ppl asking 20-22m for it recently when it wasn't long ago it was 15m -_- ) is needed as ghost ring which many claw ninja use for its -HP, after 200 becomes +HP gear. This is also probably the class that's used the most in iruna(thus I say common and generic) it's also the reason high wizard would be a good pick because many of these lazy buggers that are ninja generally never carry MP pots and are always looking for an hw to replenish their MP. Only thing with this build for this class tho is it gets really...exceedingly...boring with no buffs for pt members(only class this is the case for) and pretty well just the same 3 skills over and over with little to no variation, but, having the highest survival as long as they keep stocked up with vaccines it's 1 of the easier classes to solo mq with.
Magic ninja tho which is built to start I think much like some assassins, has a whole range of skills that are each awesome and groovy in their own way (only based on heresay as being so many of the generic build of ninja in the game I have yet to actually see a magic ninja in action) and could be really fun in the long run I think.
Aaand I think that...pretty well covers it. Only classes I haven't mentioned are gladiator because tbh lol I really don't know a terrible lot about it but
asteg might have some ideas/advice on if and how this class could work to a newer players advantage. And samurai which is the other special classes, but I thought it might be confusing if I tried explaining about it here and it's very very expensive which I know monk I mentioned is as well but samu for a new player would take a fair deal to figure out.