I would consider Denon or HK
I would say both Denon and HK have better amplifier sections than any of the
brands you mentioned. Have better reputation...and personally, IMO, look better. I have a Denon 3805 which is higher priced than those models you mentioned but you can get a 2105 or 2805 for the $400-$700 range you are seeking. I'm less familiar with the HK model numbers but check out their website and I'm sure they'll steer you in the right direction.
If you're going strictly for home theater I'd say Yamaha...they're known for their innovative DSP modes, THX certifications, and what not. I think the Denon/HK will give you a better soundstage, dynamic headroom, and cleaner
sound. I've got nothing against Pioneer or Onkyo...I just think they're a
notch below Denon and HK.
That's one opinion...I'm sure we'll hear different ones...