Which is your pick, and why?

Sonic and All Stars Racing Transformed... Its like Mario Kart but with 90% of the cast/powerups that no one cares about

LBP Karting.

Fun and amazing levels.

I second Transformed; the morphing between driving/flying/boating was cool, levels were highly dynamic, and the Wii U version has 5-player splitscreen with the Gamepad, which was AWESOME at the party where I played it.

I have played all of those except for Sonic Transformed, and I can honestly say that I didn't particularly enjoy any of them. And none of them were a patch on Mario Kart Wii, which itself was a big step down over Mario Kart Double Dash.

I think Modnation was my favourite of the 3, but still, that's not massive praise.

Not a great gen for kart racers. Give me a PS1 era of Speed Freaks/CTR/DKR to challenge Mario.

Maybe Sonic Transformed will be the game to convert me.

Blur..........

Angry Birds Go!

I'd recommend it; I found it a much  better Karting game than the others on the list.

Blur.........
Controls were almost perfect.
Tracks were varied and felt natural.
Cars and vehicles were also varied, from trucks, they all felt different and controlled as best.
Power-Ups were awesome.
Co-Op races were also fun and felt like a nice team racing game.
Matchmaking was spot on.

- My list of Best arcade racer of last gen that I played.
Sonic Racing Transformed 7/10
Split/Second 7.5/10
Burnout Paradise 8/10
Grid 2 8/10
GT 6 9/10
LBP Karting 7.8/10
Blur 9/10

If you didn't get it free on PS+ then I'd recommend trying the demo.  You might like it, but I didn't really like it.  The game felt like a kart racer that was really heavy floaty feeling.  It didn't feel like you had any sort of quick fluid control like most of  the other kart racers I've played.  Since I really didn't care about any of the characters in the game I had no reason to keep playing the game.  I deleted it shortly after.