My best bet is Coinbase.com if you're a newbie and need to convert fiat into crypto. If you want a wider selection of tokens probably check out Binance.com . If you want something that is easy to use but has a wide variety of tokens, Huobi is coming out with a new virtual currency platform HBUS.com so might be one to look  out for. They haven't launched yet but I'm planning on signing up for the email list.