I have the Pioneers, and like most people who have them, I think they are good speakers, great when you consider the price. On your list, I think the only other speaker I would consider is the Bostons. If you can handle white, you can get them from Accessories for less for 120 each. Also, A4L has the KEF C7's for 220 each. They are listed at 38 inches. I've never heard the C series, but the Q series is very good. The Bostons are new, the KEF's are open box.
Does the 500 include the center or is the center extra?
The Pioneers never sound loud in store, their sensitivity is definitely on the low side, but when you get them home and in your own listening environment you'll find that they do can go quite loud.