Good Tower Defense game?

[Rez09]

Dungeon Defender or some such

I love Dungeon Defenders.
It's a lot different than most Tower Defense games, though, as your character is almost as important to the defense as the towers you put up, and you fight alongside your defenses as you run around collecting loot and mana for upgrades during the matches. It's a great experience if you can find people to play with, since each character contributes different things to your defenses and *most* are worth having around, allowing your team to delve into higher difficulties earlier and hunt for better equipment without having to level and gear multiple characters yourself as you go along.

Orcs Must Die! is a comparable experience, though there isn't any emphasis on randomly generated loot and much more on your character to uphold your defenses. It also has a combo system that rewards the player more coins for better, more elaborate trap setups, something a bit more important to rely on in harder stages and difficulties.

For standard tower defense, well . . . I admit I'm not too familiar with the genre, but I did own Ninja Town on the DS, which a fun, albeit fairly easy, tower defense game that you might be interested in.

EDIT: Now that I think about it, and these titles are way off base from tower defense, but you might enjoy the Deception series of games as well. Instead of placing towers that defend a goal line, you place down traps in a mansion to kill enemies that are (usually) attempting to chase you down, and between stages you can research and upgrade new traps. There's a bit of devilish humor as well as that same 'lead the enemies through your defenses' mindset I associate with Tower Defense games, so I thought it might be worth mentioning. If you are interested, there are five games in the series, 3 on the Ps1, 1 on the PS2, and 1 on the PS3/Vita, though I'd recommend against the first game, as it is a vastly different experience from the rest of the series, and the most recent one is FAR too fanservicy for my appreciation. The middle three titles are all rather good, though.