Need a Speaker Recommendation

So, I'm putting together a secondary system composed of used components. My budget for the speakers will be in the $400-$700 range. The speakers will be paired with a Rotel rsx-1056, which I believe produces 100 watts X 2 into 8 ohms. So far, I've been mainly considering B&W speakers because I am most familiar with them (leaning towards 603 S2 or 602 S3). However, I'd like to hear any recommendations you guys have for an alternative speaker that can be found used in this price range, and pairs well with the Rotel(any brand, bookshelf or floorstander). The room is square shaped and approx 18' X 18' with a very high ceiling. I appreciate any advice you guys have--and please take used availability into consideration. Thanks.