For current market the best ones are BTC and ETH without a doubt! Going for alts may be not very wise for current situation, market is still very volatile.
First check the coinmarketcap observe the top 10 to 20 then have some research for the coins which you think is really good in your sight anyway. Then once you prove that it is potentials and deserving to buy, do it only on buying what you can afford to loose. Like for example Ethreum, Qtum, Waves, Xem, and Neo.