Its really going to come down to what you like as a "toy" car.
My CSVT is my daily driver, and I like it that way. My 94 Cobra is my "toy car" doesn't get driven much, usually because I'm messing with something or other on it for fun.
My 94 Cobra is over a second quicker in the 1/4 mile, stock vs. stock w/ the contour, and that's w/ me driving the Cobra like a grandma. The Cobra is also much quicker around anything bigger than an autoX course, even in stock form. And with the Mustang, there is a lot of easy stuff to do to tighten up the handling significantly also.
And pay no attention to the idiots that say RWD is impossible in the winter. It is certainly doable with the right tires, and a little self control. No matter what you are driving, you shouldn't be using summer performance tires in the winter. Get proper winter tires if you are somewhere that gets more than a tiny bit of snow; it will make driving easier, and even more fun. This goes for any kind of car, even FWD. RWD is no more difficult in the snow, just different, and requires a little practice is all.
I've said all that to say this; drive both, and pick what you like best. Both are good choices, depending on your personal preferences.
Now, from a practical standpoint, if you get a Mustang, go for a 94-95 GT or Cobra, you will get a better starting platform for less money, and modifications will be cheaper and easier for more power than for later cars within your budget. If you go for the CSVT, your budget likely limits you to a 98, 98.5 if you are looking for a nice car, though deals can be had for any year. And there are no major differences between any of the CSVT's that should be show-stoppers for any given year.
