As i am new to this collecting thing and as i want to do it right, i was wondering which aes model you would suggest to me and for which reason?
maybe you can give some pros and cons to each of the three: PAL, US and JAPANESE.
PAL (Euro) AES has English language, but has 50hz video output, although it is easy to mod the system to get 60hz. But some people think it's better to leave AES consoles as they are, without modding them. Mods should only be done if they're absolutely necessary.
US AES has English language, but some games don't have blood. The English translation is "Engrish", so it's not always easy to follow a storyline, even though it's in English (for example the Samurai Shodown and KOF storylines).
Japanese AES has Japanese language, but all games have blood. Which often doesn't matter that much, as most games can played without knowing the language, as they are simple arcade games.
The best solution is a Unibios, but you can buy a CMVS, or a MVS board and supergun, and have one in those instead (in addition to an AES console and MVS adaptor). Or you could get one professionally installed. Adding a socket to an AES is quite difficult to do yourself.
As far as board revisions, you would go for the one with the best RGB (rather than the best composite). But I don't know if serial no.s correlate consistently with board revisions, and a seller on ebay will usually only give you the serial number.