I would buy both MS3 and XX if only you could turn that shitty graphic filter off... Same for KoF98, if I remember correctly I read it had some issues related to english translation (or lack of?).
Do you guys know if there's any similar crap in Sky Stage? I tried the demo months ago, and even if it wasn't great, I thought it could have been way worse.
If you still have a PS2 lying around I'd get 98UM on that. It's a better version of the game that's in English and you can get it now for about the same price you would buying the game on LIVE. But if those aren't deal breakers then 400 is a good entry price to get it.
I'd suggest 2002 UM for the fact this is the only way you can get the game in English. And it's based of the Tokugeki Editon sans NeoGeo Mode and the Color Edit so your playing the damn near latest update outside of Revenge in the arcades now.
I'd take XX over 3 just because of the deal. The game is worth 600 because it was worth 1200. And for an extra 80 you get Leona. 3 is still crack though so get that too if XX isn't enough of a fix for you. And in 3 I think you can adjust the filters. I don't have my XBOX around to check but somebody will chime in if I'm wrong.
Trouble Witches NEO is damn good. I picked it up last time it was on sale. So if you're looking for a decent horizontal SHMUP that happens to be on sale this week then get this one.
KOF SkyStage gets an OK from me. A lot of hardcore fans of the genre tend to disagree but for 400 its a steal. I'm spoiled on NeoGeo Heroes Ultimate Shooting which is a better version of SkyStage in my view. But I bought SkyStage Day 1 and I had fun with it though. So take that for what you will.