I'm afraid, there is really no way to be certain of the altcoin that will prolly do well next year and down the road in the future, there are quite a lot of altcoins, many of which to not even have a use case and are either a pump and dump coin, or just basically launched by scammers to take money away from investor. Then again, if you ask people for such an opinion, they always tend to choose the coin that they are holding, so they can somewhat hype it and cause an increase in it's price; having said that, what needs to be done is for individual investors to do their own research and come to the conclusion of the altcoin they think is good and if they have the funds, they should go on and invest.