Difficult question. Three coins for investing are very few. It is likely that all three coins will not bring profit, but only losses. In my portfolio absolutely different coins and tokens. In the long term, I keep Stratis, Stellar, Cardano. In the spring I expect to get a good profit from Aion. In summer, I very much count on the OAX and the Cindicator. For daily trading I use about 10 different tokens.
The whole point in investing is basing it on knowledge and the probability of success, making it more likely to bring profit rather than loss. 3 coins or 10, if you pick the right ones you will profit. It's good to have a diversified portofolio though.