Sonic Colors
They are both great games, but i'd say sonic colors
Yes, there are Sonic games after Sonic Unleashed. At the time of writing, the latest will be Sonic Generations.
Here are the Sonic games for the Wii: Sonic and the Secret Rings, Mario and Sonic at the Olympic games, Sonic Unleashed, Sonic and the Black Knight, Sonic Riders Zero Gravity, Sonic Colors, Sonic The Hedgehog, Sonic & SEGA All-Stars Racing, Sonic made an appearance in Super Smash Bros. Brawl, but that's not an actual Sonic game.
LOADS! Sonic colors, sonic rush, Mario and sonic at the Olympic games (Now there's 2012 Olympics and winter Olympics!) Sonic unleashed, Sonic and the secret rings, sonic generations, sonic heroes, sonic adventure 2 battle, sonic adventure, sonic 2006, the original sonic the hedgehog AND MUCH MORE
sonic adventure 3? sonic unleashed 2? or sonic heroes 2?
Other than the extra abilities in several games like Sonic Unleashed, or Sonic Colors, Sonic doesn't 'gain' powers. He always had his famous speed. Along with the ability to use the chaos emeralds to turn into Super Sonic.
So far just sonic unleashed.
I think the only one out so far is Mario & Sonic at the Winter Olympic Games.
I believe he hasn't liked anyone in the games, thus far. Especially in Unleashed, where his only real companion is Chip.
Simpsons Game, sonic unleashed, other sonic games
Yes, there will be. In fact, more have already come out.
The Sonic the Hedgehog game franchise has these games: Sonic the Hedgehog, Sonic the Hedgehog 2, Sonic the Hedgehog Spinball, Sonic the Hedgehog 3, Sonic & Knuckles, Sonic Adventure, Sonic Adventure 2 Battle, Sonic Advance, Sonic Mega Collection, Sonic Heroes, Sonic Mega Collection Plus, Sonic Rush, Sonic and the Secret Rings, Sonic the Hedgehog (mobile), Sonic Unleashed, Sonic & Sega All-Stars Racing, Sonic Colors, and Sonic Generations.