Meh... I voted Nitro. I really enjoy all the new tracks... even though I only played the N64 and GBA versions previously. Since I'm not familiar with the SNES or GCN versions, some of the retro tracks were new to me, the most fun ones being Luigi Circuit GCN and Baby Park. Nirto feeds me with a bunch of new things, each having its own quirk, although Figure-8 is pretty boring, especially online when I have to snake in order to keep up with the other snakers on that course. I love Yoshi Falls and Luigi Mansion because i know exactly how to race them and which shortcuts are the best. Then there are the obnoxious Nitro courses, like Cheep Cheep Beach and (don't hurt me) Waluigi Pinball, the overly fun ones such as Airship Fortress, Shroom Bridge and Peach Gardens, and the remakes like Wario Stadium, Bowser Castle and Rainbow Road. Still, I think the retro courses are much harder than the nitro. Well that's enough blabbing from me, there's my opinion for you.