Guardian - While I'm learning EQ2, the guardian gives me a lot of room for error. (If you've seen my other posts about my 1337 pulling skills :P )
The Shadowknight was still my favorite to play so far, but as expected, didn't tank anywhere near as well as the Guardian..I'll probably experiment with a Berserker too before I make my final choice. I'm 100% sure I wasn't playing the Shadowknight to it's fullest. - I do have 1 regret in that I chose a HUGE Barbarian for my current Guardian..and it's a nightmare to see around in small dungeons right now.

Templar + Warden - I want a main healer and I liked the ports from the druid. I tried a mystic in place of the Templar, but a lot of the druid and mystic buffs seemed kind of the same. I'm sure that would have changed the more I played.

Conjuror - I played a mage in EQ1 so I thought what the heck. BUT, after working on that chart, I'm not sure just how much the Conjuror brings to the multi-box group. But I'm not sure what I'd replace it with just yet.

Troubador - I just like it.. I'm never out of power..and running is nice when I'm not on a mount. Lots of really nice buffs including a group aggro reduction and a targeted aggro imrpovement for the tank. Also has a group Evac!

Warlock - I played a Wizard first, but it just didn't seem like it was doing much. One of my alt-armys used a Warlock, and it just seemed like it was kicking butt and taking names. I wanted the ports from this class too..so it was either Wizard or Warlock. But to be honest, I've yet to use a spire port.