This is definitely a good problem to have! I'm not sure what I would pick either, I love the GT500 wheels and the Saleen wheels. However, if you're just going no stripe or anything, I may go with a gloss black finish! Or you could go with a Matte Black stripe and wheel combo, which would be really cool.
This is just a suggestion! Let me know if I can be of any assistance. I'm confident that you'll be really happy with your new wheels regardless! Our Mustang Experts are here Monday-Friday from 9AM-9PM EST and Saturdays from 9AM-5:30PM EST. If you want to hit them up, their number is 866.727.1266. I can also have one of them call you directly.