I would choose Denon from the brands you listed. The others are fine [although I would avoid Sony] but D&M Holding [Denon's parent company] is just my personal favorite. I use a Marantz pre/pro which is also a D & M brand.
I ordered my Klipsch's via Amazon. It would be somewhat of a hassle to send them back if you didn't like them but it is possible. Always check with the seller. I'm not personally familiar with Elac but I do own both SVS and Axiom speakers and have for many years. Both are excellent and will...
Welcome! I have the RP280F's and RP504C center speaker in my room and they are pretty awesome but, as @Dave Upton alludes, speaker preference is a highly subjective thing. My advice would be to take some time and listen to a few but do it in your environment, not a showroom. The better...