Go with whatever car you like best... they're all going to be close to the same lap times with a little variation here and there. That TOM's Supra though is a GT1 classic that I must own.
Reason, well the RX7 is my favorite Japanese car and have always had some type of race version in all the GT's. Plus its the only Super GT car I have in GT5, and its drives awesome. I used it for the GT World Championship and highly recommend.
Petronas Toms. 2009's Team & Drivers Champions but since that's not included in your poll the Toyota Supra is a good buy. Castrol one if you want it premium but the Woodone was great in GT4 if you'd settle with standard.