I got my first Neo Geo in 2008/9. I'd always been into SNK games and wanted a Neo Geo, but I never had the money to spend (apart from the pocket color which I bought on launch). At that point I'd saved up a little bit of money and decided to splash out and treat myself to an AES.
About a year or so later I found an MVS arcade cabinet, so sold up my small AES collection to go down the MVS route. Roughly a year later the monitor died and I couldn't find a way to fix it, so I sold my MVS games and the working boards and went back to the AES.
Last year I bought myself an AES to MVS convertor and started building up another small MVS collection, then at the beginning of this year I bought myself a CMVS from Xian Xi here on the forums.
So, after all that buying and selling and changing I've finally settled for both. I have an AES, a CMVS and a nice collection of games for each.