3 choices for power amp

Unfortunately I have not heard those amps personally however from what I've read I would go with the AGD Tempo or the AGD III Duet.

Here is one source of information:

Based on my experience, you are most likely to get the best sound quality by staying within brand.

I haven't heard your three choices but have an extremely good, modern class D stereo amp.

My Coda S5.5 stereo amp, for not that much more than the above, given a side by side comparison, would make anyone considering class D reconsider.

I believe there are others in the following link that feel the same way.

Coda S5.5 Class A Stereo Amp Thread

my recommendation is the same as vinyl valet stick with the amp within your family I think it'll probably sound the best.

I've owned the Benchmark and currently own the Atma-Sphere Class D.   I personally think they sound pretty different.   

I found the AHB2 to be extremely clean sounding, very solid bass, and highly resolving.   It had a super black background and you could hear into the recording like crazy.   I also found it to be a little lean sounding and 2 dimensional, not much front to back soundstage.   I liked it but at the time had a Pass X250.8 and preferred the big Pass amp.   The AtmaSphere has the super black background and solid bass, but sounds much more like the Pass to me.   I don't think it is as resolving as the AHB2 but it has more the color/tone of the Pass with better side to side and front to back imaging compared to the Benchmark.   To me, the AHB2 is a great tool to analyze a recording, where the Pass and AtmaSphere bring you closer to the music/soul of the recording.     My preamp is the SimAudio 740P (used on all 3 amps).   I would go with the AtmaSphere if you have the AtmaSphere preamp and am happy with the AtmaSphere sound signature.

Cheers