Hmm..
Well I would have to say, for
Super Dbz it goes something like this.
1- Trunks : Because apart from the fact I have leveled the shit out of him, the capsule corp laser sword is just so badass.
2- Cyborg Freeza : Again, I'm a sucker for the add-on stuff, I love the giant cannon, it's both ridiculous and awesome.
3- Goku : He's always my default character to fall back on, I don't like him as much as Trunks or Freeza, but it's always fun putting on the Yardrat (?) costume and spamming the hell out of Instantaneous movement
For
Shin Budokai: Another road (quite the dissapointing game, did anyone else hate the lame attempt to shake things up by moving the default camera angle?)
1- Vegetto : Mostly because of his colossally cheap auto counter move, also he looks neat.
2- Gotenks : Because Super Ghost Kamikaze attack is a lifesaver
3- Mirai Gohan : I'm not a fan of the made up transformations, but he can use the Makankosappo, which means I love him.
And finally
Budokai Tenkaichi 2/Sparking Neo
1- Tullece : Firstly, he's my absolute favourite movie character, he may be a little on the slow side, but his ability to go into sparking mode and regain health with three blast stocks more than makes up for it.
2- Mirai Trunks (Saiya-jin armor) : He's incredibly fast, but also has the ability to become a hard hitter at the cost of some speed. (Interesting side note I consider Mirai Trunks (With sword) to be the worst character in the game, he's pumped full of so many extra frames of animation that it's ridiculous.)
And finally
3- Buu saga Vegeta : Because if you start to lose, he's got great energy attacks to spam.
In the interest of keeping a long list short (ish) I skipped over the many other characters I enjoy (Super 17, Bebi Vegeta, Cell (in Super Dbz & Sparking Neo) and SSJ 4 Goku)
I play too many Dbz games.