I'm sure all the PPs with dressing recipes are well intentioned, but apparently didn't read OP's follow up post explaining why she needs store bought.
I haven't tried anything new in a while, OP, since I make my own. However, Gerrards always used to be decent. It's that odd triangular glass bottle brand you can get at regular stores like Giant. They have a raspberry vinaigrette that was pretty fancy 20 years ago

though a little sweet for my taste. They have a couple other vinaigrette options including balsamic.
Balsamic vinaigrette is going to be your safest bet for store bought. Look for ones that have the least amount of herbs floating around in it.