ETH without any doubts. Other good ones are XLM, EOS, ADA... these are my favorites among top alts. I don't think that it is a good time for small coins so I don't point them out.
In my opinion ethereum is a coin that has very good prospects in the future, even though now the price is dropping but I'm sure that ethereum will soon improve and recover, so I prefer to focus on ethereum than others.
Yes, etherum will lead in altcoins,Litecoin and Deep onion will also profit oriented.Buy according to affordability and patience for perfect time will find positive results.