Which Amp? Onkyo, Emotiva, Marantz, etc.

My 15 yrs old receiver died recently & I've the opportunity to upgrade. I'm planning to use Oppo BDP-105 in Pre/Pro mode in 5.1 setup.

I'm considering the following similarly priced ($1500-$2000) used/refurbished devices:
Amplifier: Emotiva XPR-5, MARANTZ MM8077, Onkyo PA-MC5500
Receiver: ONKYO TX-NR5010, Onkyo TX-NR3010,YAMAHA RX-A3020, DENON AVR-4520CI & MARANTZ SR7007.

I do understand that the separate Amp would provide better sound & upgrade path but receivers will provide better functionality & features.

Which one would you recommend? I'm open to any other devices than the ones listed above.

Thanks for your time.
For starters, could you list the size of the room, the volume level you usually prefer(what decibel level?), the speaker models used and the old receiver model just for reference. I ask this because you have a 400 wpc amp listed, and unless your room is massive and your speakers quite large you might be buying watts you'd never use.
I agree with Runnin about sizing the amp properly to the room/speakers. More info. from you will allow us to make more informed recommendations...

Thank you guys. Here's the info requested:
Room 16x18+ with some open area, so sound can bleed
Speaker: Tyler Acoustics Linbrook System II (L, R,C)
Speaker: JBL S312 (RL, RR)
Receiver: Kenwood VR-4090B
Volume: 32
BD:Oppo 105
Tape Deck: Nakamichi RX-505

I usually watch movies but at times, like to listen to tapes.

Hope that helps!
Does that 32 mean -32, or 32db below reference? or is it 32 out of a max like 80 or 100? Either way, with your size room that's not considered very loud and you wouldn't need 400 watts per speaker IMO.

If receiver I'd tend to lean towards the Denon 4520. Or if you're feeling a little adventurous, get a separate 5 channel amp like the Emotiva XPA-5 or Outlaw Audio 7500. Then you could get a cheaper Denon like the X4000. These Denon's both have the top of the line room correction from Audyssey and that alone will amaze you compared what you are used to.
I highly recommend the Emotiva products. My friend had an XPA-2 powering Maggies via a fancy tube preamp and I was amazed at the quality of sound it produced. Considerably better than the B&K amp it replaced.
I ended up purchasing the XPA-200 amp on sale for $419 shipped to my door. I'm using it to power some home brew Usher passive subs to supplement my main Usher speakers. I could not be happier. A big thumbs up for Emotiva. They also hold their value reasonably should you decide to sell.
Well, I"d stay away from their processors. Also better to get speakers from a company that specializes in them only.
Thank you all for providing your valuable responses. I built on yours & started digging further. Read tonnes & tonnes of reviews & forum discussions.

First of all, Receiver route is definitely out. I do know that I don't need very High Power. But I anticipate SQ to go up too in high-end Amps.

So, here are the final Amp contenders with my preferences. Let me know if I am going off (I could be after burying myself in my Laptop for the last 3 days) :)
1.) Parasound A 51
1.) Emotiva XPR-5
2.) ATI 2005
2.) Outlaw 7500 or 755
2.) Parasound 5250 or 5125
2.) Theta Digital Intrepid
3.) Anthem MCA-50

Now, it all boils down to what I can get in my budget & in a decent condition.
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Hey guys! I finally bought Parasound Halo A 51 from AudioGon for $2100. Visually there are a few blemishes & it trips-off in Auto 12V setting. My first impression is that it's very heavy (95 lbs) & it gets really hot fast.

Anyway, currently listening to various types of music (stereo, XLR) & movies (5.1, RCA) & comparing notes. In a few scenes, I did hear the background music that I never heard/noticed before but nothing significant while listening to music in stereo. In defense of my previous Kenwood VR-4090 receiver (MSRP 1200/ Used 450) which I was never so attached with, I must admit that though it's 1/4th the price of A51 (MSRP 4500/ Used 2100) it was no slouch in terms of SQ & imaging.

It's almost 24 hrs since I first plugged in. Still exploring & justifying whether my purchase was worth 4 times. Will keep you posted.