only invest in Bitcoin if you are going to keep trading but if you want to grow your portfolio there are some coins on my radar like examples WAVES, ETH, NEO, SOL, XRP.
The coin you have mentioned is good for the long-term hold. but the OP wants to invest all of his money in one coin. For this Bitcoin is the best and safe investment. In the long term, he can able to gain a good profit from this.
But if I were OP, I can invest my 50% in Bitcoin and Ethereum. The rest of them are for various altcoins. Altcoins can give a good return within the short term. 10x-20x is also very possible in altcoins. Now accumulating Matic, Cardano, Tomochain, SXP, SRM, SOL, ETH, BNB, GRT, and NWC. Hope soon they will make me rich, I am ready to hold those coins for a minimum of 1 year.