I'm playing a ranged Shadow Warrior around level 56 right now, and it's probably my most favorite character because he gives you so much that you can do to react to situations and be powerful, so many interesting moves, and the lack of bad weaknesses means I can relax and just enjoy playing. He's got offense and defense boosts, great buffs, a jump, generous adaptability in the builds, fun weapon damage CA mods, various ways to get Area of Effect and big single target damage. That said, most of his uniqueness seems to be locked in Astral Lord, which I haven't been able to use.
My second favorite character, and my previous favorite, is the Dryad. The two things I don't like about the Dryad is the terrible vulnerability to fire and the lack of a good offensive boost for a ranged Capricious dryad. I feel very good playing a Dryad, but if I step away from the controller on PS3, she could die to a fire mob, despite being virtually immortal elsewhere.
I want to love the Temple Guardian because there are so many neat CAs, but you almost can't use some of them, and most of them are almost useless at a low level. That said, I did recently discover how powerful a low level Source Warden is against Kobolds. I'm in the process of tinkering with a ranged TG using a one handed blaster. Early signs are that it's going to be good.
I think my least favorite character, minding I haven't played Dragon Mage, is the High Elf. She's fun to play, but I feel like too many of her CAs feel redundant, like having two AoEs in Arrant Pyromancer. When you're trying to make a Magic Coup build, it's really disappointing that almost none of the offensive spells have debuffing bonus choices. You have to choose a tree for a defensive buff because you have almost no defensive skills, but I think Incendiary Shower and Cascading Shroud are the only CAs there that have any use for a melee high elf. One of the things I enjoy is planning out builds, and every time I try to make a magic coup build, I feel like my hands are tied.