There is a lot of different change were evryone can buy Bitcoin. Anyone can suggest some good and fast change for buy BTC and if is possible use prepaid card with no high fee like Coinbase.
Exchanges should be joined based on what currency you're trying to purchase, only second to whether or not they're scammers. Each exchange supports a different amount of altcoins, so it really depends on what coins you're trying to invest in.
Of course, you'll want to find an exchange that supports some promising projects. There's no need to go on exchanges that have support for terrible coins. I've heard that EtherDelta doesn't have many good coins available. I currently use Binance for the altcoins I've wanted to invest in.