I'm doing a little research on tower defense games, and I was hoping some of you with a little more knowledge could help me out.

I'm looking for what maybe you would consider to be the top tier of tower defense games in 2 main areas; gameplay and graphics (If you think one game has the best of both that works too).

Thanks for pointing me in the right direction if you can.

Bloons Tower Defence Is absolutely phenomenal - latest version here

Gemcraft is just as awesome (if not more) - latest version here

Both I consider to be the best of the genre in both gameplay and graphics (moslty gameplay) - The difference is Bloons has more of a light-hearted theme (cartoon monkeys popping balloons) VS. Gemcraft with a more deep/serious medieval-ish vibe

Buy Warcraft 3 from walmart for $19.99, package includes its expansion, play the Frozen Throne expansion and play the tower defenses and mauls that are available for free there.

Pixel Junk Monsters ps3

plants vs Zombies pc/mac

Plants vs Zombies 
Ninjatown(DS)

Ninjatown is actually quite awesome 

people have already mentioned it, but I can't recommend Plants vs Zombies enough

Oh yeeeeeaaaah - I fogot that PvsZ's genre was tower defence roflrofl

Plants vs Zombies >>>> All the other games I mentioned :D

(It's not free to play like the other two though)

someone please help me !, I know this is offtopic, but I'm unable to make a thread. People tell me: "the Thread butten is on the top right of the screen, BUT IT"S FREAKING NOT THERE.

I can't even poste a screenshot to show it....

Thanks everyone!

I've been playing a bunch of the ones you've recommended and I'm getting a feel for whats out there.

I'm actually asking this because I'm looking into creating my own tower defense game (Part for project/experience and also possibly to get it onto game/app stores). 

I've been googling for a while, but can anyone with an iPhone or something similar direct me to td games with good 3D graphics?  Once again I just want to see whats currently out there.

To make a thread you have to be in a forum I'm pretty sure.  Go to a forum and it will be in the upper right (not in a thread)