I like the mach 1 wheels a lot. They are very sharp and not that common. The bullitt and FR500 wheels are everywhere it seems like. Having said that, do what you like the most. It sounds like this is discretionary money that you can spend as you wish, so do as such.
I actually had 5 different sets of wheels on my 88 mustang during the time I owned it (stock wire spoke 14's, weld 14's, 16" ponys, 17" 5-star 99+ GT and 17" 05+ GT wheels). It was fun, and I usually ended up switching because I got some really good deals. I would have been perfectly happy if I had always kept the pony wheels though. Keep that in mind... reality is, most people won't see the difference and even for yourself, the difference will be subtle.