I own an Axiom and an 2009 Aqua 888. I personally like my Axiom twice as much as my 888. The 888 is great but tends to lean alot in the middle of tricks, even with a KK. And you might say "oh thats just because your throw was bad"....Its not my throw. Yes, Hubstacks are fun at first but you will soon tire of them because well....just because. They're only Hubstacks, you cant really do any tricks with them or anything. And because of the hubstacks it makes it very hard to do thumb grinds. I personally rate the 888 on a scale of 1-10 (compared to the Axiom) as a 6. But this is compared to the Axiom not just rated as another yoyo.
The Axoim however is incredibly easy to do thumb grinds on, as well as many other grinds. My Axiom never leans at all for me. Its one of the smoothest yoyos ive ever played if taken care of properly. And besides you can never go wrong with a YYJ yoyo! You could offer me 3 888's or 1 Axiom and I would take the Axiom. I know that may not make complete sense but you get the point.
So I highly recomend the Axiom over the 888. Get The Axiom!