Long time ago (2yrs) I was on the same position you are now. I was deciding between Axiom and Aperion tower speakers. After reading many reviews, asking in the forums of each manufacturer, having some patience and calling each one, I went for Axiom Loudspeakers.

I must say, that Axiom customer service is second to none. I can not see any one with better CS. I do have also Outlaw products (770, ICBM, Velo SMS from their website), and as stated in the thread, they are a close second. I do not know Aperion CS, but investigating a lot on their forums, I think that better than Axiom they are not, maybe close, but not the same.

Sound wise, I havent heard the Aperions, but the Axioms are everything they say they are. They are very linear, almost no colored, but unforgiving of bad recordings. Some people defines them as sibilant, but that is because bad recordings, because with good CD's they do not sound like that. Stereo imaging is awesone with the M22 and the M80 (I have both), and the clarity is unbelievable. They can fill large rooms with ease. There is no better surrounds in the market than the QS series from Axiom, as reviewed many times around, as the Quadpolar setup have advantages over the dipole / bipole setups.

I have only A/B my speakers against BG's Radia X3 (hybrid) and Polk's Rti10, and Axioms were the choice I made, because I did like the sound of them, I like the price of them, and the CS is the best I have seen so far.

Getting back to the towers: which towers are you considering? I mean, which one are you deciding between? Which amp / receiver are you going to use to feed them? I guess that in order to compare with the dual 6.5" from the Aperion 633, you will have to go with either the M80 or the M60. Price are slightly similar to the M60, and both have dual 6.5" woofers, but the Axiom is giving an extra 5.25" midrange. I strongly advise to listen to both brands.

I will suggest getting both towers within the 30day guarantee and listen to them both, and post back as it will be very nice to see what conclusion you draw. I am still curious of the X-over tech of the Aperions.