I prefer Aronson stack, just because I can shuffle into it. You feel so accomplish once got the full stack memorized.

Sounds interesting, I never heard about a simple way to come into the Aronson stack from NDO. Can you give details ?

I'm a bit confused by that statement - obviously, as a Mnemonica user I know a few simple ways to shuffle and/or perform tricks to get into and out of that, but for Aronson stack, the only real method for getting into it aside from stacking card by card is the one put forth in Eric Richardson's Aronson stack ebook series on Vanishing Inc in Vol 3, Tour. It's a workable method, but I wouldn't say it is simple. Still, if you do stack work, Richardson's ebooks are worth reading, even if you don't use the Aronson stack.

Learn either one. They both have nice properties built in. Some time later, learn the other.