The first Guilty Gear is still the most intense fighting game I've ever played. I really like the entire series, you couldn't go worng with any of them but if I was you and I wanted to start with this series I feel that Accent Core+ might be a bit too much too handle if you are not used to the pace of the series. AC+ separates the noobs from the veterans real quick and most people that play the game hardly scratch the surface.
I would start with Guilty Gear X or XX (X2) for the PS2 'cause is cheap, relatively easy to find and it has everything that makes Guilty Gear unique in spades. If you have a DC go with GGX and get a VGA box, I still remember teh first time I did that, I seriously felt the wheels of progress rolling when I played that game.
The whole ISUKA debacle here is just so wrong. ISUKA is a great game, however I can see why people hate the turning button, after all I hate the Block button on MK games. Well, I was so ready for ISUKA 'cause the first Guilty Gear used to have a slow turn around time and you could get punish easily when attempting crossups and so on, there was this trick though, if you hit the respect button your character will trun around inmediately so I used it all the time so in short the whole trun around technic used in ISUKA was something already on the works since the first inception of the series. THe funny thing is that people are so obssesed with the turn around button they don't even realize that even after you get a hold of doing that you still have another 3 commands for switching planes. ISUKA is a very intricate fighter, very technical ala FATAL FURY 3 which is also a fantastic game and one of the most technical games I have played.
