Mine would be muscle type cars. I'm currently rebuilding/restoring a '78 Camaro. I built a 385 stroker motor for it, had the 8.5" 10 bolt rear end completely rebuilt. I went with a Yukon Duragrip posi unit and 3.42 gears. The current TH350 is a little weak, I'm having a pretty stout TH350 built as I type this. The car needs body, interior work and I'm going to rebuild the entire suspension. Slowly but surely it'll get done.
My favorite muscle car is a '67 SS Chevelle. I'd like to find a Chevelle or Malibu and make my own SS out of it. I'd build a 500 plus inch big block with a 5 speed Tremec TKO and a 12 bolt rear end. I also like '70-'72 Monte Carlo's. I'd build the same 500 plus inch big block and 12 bolt rear end but I'd go with a 4L80E automatic overdrive transmission in it. A '70 split bumper Camaro with a small block 434 stroker, 5 speed Tremec TKO would be nice.
I like '69-'70 Mustangs too. Either a small block 408 stroker or a big block with a 5 speed Tremec TKO and a 9".
My favorite Mopar is a 71 Plymouth Road Runner (I love that body style). Either a small block 420 stroker or a 500 plus inch big block. Again, a 5 speed Tremec TKO with a 8 3/4" or a Dana 60. I also like '67 GTX's and '69 Dodge Super Bee's (my uncle has both, the GTX has a 440 and Super Bee has the ORIGINAL 440 six pac!).
I'm not really brand loyal. I just have way more experience with Chevy products then other brands. I like a lot of different cars though. Pontiac's, Buick's, Oldsmobile's, Dodge's ect. Never really got into AMC though, not knocking them, just didn't get into them.