Hi Alfredo,
I have listened to both Aragon and Rotel amps previously, and my preference is for Aragon. I find that Aragon has more depth and detail.....but that is just my preference....
As crazy as it sounds, I would recommend that you go for 2 five-channel Aragon amplifiers for your 7-speaker configuration. I have found that I got the best result through bi-amping (2-channels for 1 speaker), rather than a single-channel for 1 speaker. Even though the single channel has larger power output on the 2-channel amp (300 watts vs. 200 watts), the sound will come through with much more dynamic and resolution when the speakers are bi-amped with the five channel amp. I have tried out this type of arrangement, and what I found was that bi-amping always sounded better with comparable amps. The only caveat to bi-amping is to make sure that the amps have the same gain. This will be ensured when you use the same amp.
Currently, I am using a Krell KAV-1500 (5-channel amp) and a Krell KAV-350a/3 (3-channel amp), to drive my 5-speaker B&W Nautilus 801/HTM-1/805 set up. I use six channels to bi-amp my two front and center speakers, and the remaining two channels for the rear surrounds.
So with 2 five-channel amps, you can use six channels for the two front and center speakers and the remaining four channels for the two side and two surround speakers....
Anyway, enjoy building your system and happy listening.....