Yoshi Circuit and Hyrule Circuit (I am still wondering why they didn't name it "Hyrule Castle") are my favorite tracks in the pack so far, it's hard to decide which one I like most, but at the moment I would go with Yoshi Circuit, because of the nice nostalgic Double Dash-feeling^^
I like Ice Ice Outpost design-wise a lot, but Nintendo failed miserably with the shortcuts on this track. They should have taken the hopping physics into account and made the ramps cut a little bit more of the corners

This could have made the track way more entertaining.
Mute City is what to expect from a F-Zero-track, very fast paced with crazy gravity, I like it.
My least favorite track is SNES Rainbow Road. The graphics look really nice, but I'm at that point where I actually had enough of this course. It got remade so often, it just doesn't feel special anymore. I had preferred a SNES Bowser Castle or SNES Ghost Valley

Btw.: When will the DLC track charts go online on the Players' Page? I know there has to be worked out some stuff for the rankings, but really, the DLC was announced for such a long time now - wasn't there enough time to prepare things?