i have Sonic & Sega All-Stars Racing , should i still buy modnation racer?

[Shadowfest3]

I have Sonic All-Stars Racing for the 360 but I really would like to buy Modnation Racers.  The demo was pretty fun but it only had one track to try out.  Anyways, I also would like to buy Blur as it seems as if it would be fun as well.