The Audioengine is probably the best of the group you mentioned. I haven’t heard the A5, but the A2 sounds better than the ProMedia (which actually doesn’t sound bad). However, you’re going to need a sub with the A5, so the bottom-line cost (and sound quality) is going to be higher than the rest.
I haven’t heard the others you mentioned, but it’s probably a toss-up. They all get good reviews. However, Bose has a reputation among knowledgeable audiophiles as being a poor value, meaning you can typically get better sound quality from other manufactures for less money, so I’d probably rule that one out based on that.
Frankly with one exception, anytime I’ve bought speakers based on someone else’s recommendation I’ve been disappointed. Really, it’s best to audition speakers first-hand and make your own decision.
Regards,
Wayne A. Pflughaupt