I think, the most interesting skill tree is juggernaut because:
- It won't make battle very long (quick kill, quick death). Long battle can make game boring when you play with another 3 friends.
- It brings new game mechanic, based on helth bank. Now there is no such bank for spells in D:OS (like mana in other games), we have cooldown instead. With juggernaut it will be able to make powerfull skills without cooldown (but with cost of some percent of maximum hp). In fact, even old skills from fighter tree without cd (but with hp cost) can make this class more interesting. Or at least with minimal cooldowns.
- It can be usefull both in competetive and cooperative mods. Juggernaut can be combined with some other classes (healer, slayer, etc.)
I think, the least interesting tree is Trap Master. I suppose it will be just another version of ranger without arrows, but traps. Fire trap, ice trap, charm trap etc.
The main problem - lots of battles will end before you can use traps. It is far easier to throw fireball in foe. Another one, how trap master will defeat player, who sudden declare war? Theoretically, it can. Practically, depends on realization.
By the way, Summoner has similar problem. It is far easier and faster to throw fireball (expecially in pvp), and summoner requires some time to prepare to battle. On the other hand, developer can allows to summoner to has one permanent creature.
Polymorpher can change himself. But what will be changed in gameplay? For sure, player will get new character model and attributes. Probably, he will be able to get increased attack raneged, changed damage type (fire, ice, etc. - hello, ranger). May be he will get skill "stone skin" and become a tank.
Do you rememer polymorh spells and abilities from D&D? They can be efficient, but not so interesting, in fact.
Bard. Developers can easily make this class very popular. They simply should allow it to declare war with friend whenever he wants, and forbid such ability for other classes =)
Due to Bard is very charismatic asshole
