I saw some screenshots and some ideas for last stand 2 and I think that it is going to be pretty good. I hav not seen anything for Sonny though except the Blue girl on the title picture. On last stand 2 you will be able to search which rooms you want for survivors. There is also like 5 new guns including a bow and arrow and even grenades! You can also lend your friends your own guns.
Well Last Stand:Stand Laster is supposed to be coming out sometime before grand theft auto 4 comes out. As for Sonny 2, I think it is coming out in a couple of months.
I myself cannot choose which one is my favorite, I love the graphics of Last Stand and I think the gameplay is awesome. As for Sonny, I also like the graphics and art and it was one of the best rpg turn-based games I have ever played.