I am heading for smaller investment (about 1500 dollar), I want to buy mostly btc maybe some alts.
Friend of min recommended bitfinex.com because of the margin options.
Your friend is a dumb, how can he tell you that marging options are the best thing of bitfinex?
You are going to lose all your money in there.
if you do not even know what the hell are the "marging" positions then do not even think about opening one, because they are working like a broker with long/short positions, if you do not know how it works, you will make a mess in there and probably you will lose it all.
Be careful, if you want to use a simple exchange, just use bitfinex, but only for trading and holding purposes.
Good luck