ETH, XRP and BCH re my three picks because they top at the rankings of alts so it will more likely that they are the ones who can produce the most profit aside from BTC. There are more other coins out there but I still don't research about them so I have no idea how well they will react in the bull run. It will be a chaos if all alts will boom and many can fall down because of the sudden increase in the prices. It will wise to invest in different coins.