As far as GG games go, I agree Accent Core is the way the go. Its a phenomenal game and really the only one you will need unless you want to go back and trace the game's history/roots (which I sometimes like to do).
As far as Blazblue goes, I enjoy it, but nearly as much as Guilty Gear...
HIJACK
In terms of Atomiswave games, would you go Guilty Gear X, or Guilty Gear Isuka?
How is Guilty Gear X 1.5 on the Atomiswave?
I've owned both games on atomiswave and think they both have their own merits. I believe GG X 1.5 is essentially the same as the DC and PS2 ports. The game looks fantastic in hi res. The only thing is that the game is pretty expensive as its hard to come by. I believe I bought it for $175 and I was a tad bit disappointed just because the home ports were so good I felt it was an uneccessary expense and sold it off.
GG Isuka is good, I enjoyed it. It has the weird mechanic of hitting a button to turn around, but honestly, I didnt find it too hard to get used to. After some practing, it becomes second nature. And some of the fights become pretty insane. And also, the game looks great in hi res. Plus, it is pretty reasonable in terms of cost.
But as w/ GG 1.5...the home port was really good too. So I ended up selling both games (and all my AW stuff) awhile back. For me, the ports are just fine. But if you are a committed arcade/pcb guy, then get them both as I think they are 2 of the more enjoyable games on the AW.