I think rogerborg has a good point. Have you played before?
If you haven't, the best one is probably one that a site rents to you. Rent the first at least 3 times. Yes it will cost you a bit extra but I swear there are thousands of people who have thought airsoft was the dogs danglies on YouTube, maybe had an awesome first game, but by their 3rd/4th game have lost the hype and they've sunk a small fortune into the hobby and you never get back what you've paid when selling it.
It's also a great way to get chatting to other players on site, airsofters love talking about their gear and guns, chat to them, ask to hold them, test shoot them etc. You'll get a better understanding of what you want, what's available and you'll at least get a bit chatty with the other players.
If you haven't played before then you'll need to get a two tone, which if you get into the sport you'll probably be keen to replace, so you won't end up saving any cash.
If you have played before and like m4s personally I'd suggest a g&g m4, anyone in your price range that you like the look of. They all basically do the same thing and the quality control of g&g seems good for the money, so then just getting one you like the look of is sensible, longer barrels aren't more accurate etc. The performance and functionality of them will all be the same/very similar.
Don't like m4s? well......I'd honestly recommend sucking that up and getting an m4. You can get some great cheap ones, Parts are easy to get, they're common so onsite techs aren't working on something weird and they should be good to go out of the box from a brand like g&g or specna. Accessories, kit (chest rigs, mag pouches) are common and cheap. Also, they can be lovely.
If you really must have an AK or some other weird shaped one, by the time you can justify spending the money you'll be in a better place to understand what's good, what you're looking for etc. Just don't be one of those people who is like.....I've just bought this gnu , is it any good?