If you are already anticipating for the next halving then why not simply hodl bitcoin as you wait. There are lots of project that might have promissory ROI but to be on the safe side and avoid falling for scam project stick to Bitcoin except you are willing to do your personal research on other projects. The crypto world is full of volatile assets and to stay bullish on the volatile nature is what investors live up to and keeping up to this requires research and research before investing
It is really a good choice to have bitcoin in investment portfolio if one is expecting post-halving gains. It makes no sense for them to target profits without considering bitcoin as one of the best among thousands of other altcoin, so the bottom line is that bitcoin should not be ignored.
Some other best advice in my opinion is, the OP can check the potential altcoinson the current top list including ETH, BNB or others. Of course I don't think stablecoin is the best case for long term investing, so there are only a few that might be better than picking them at random.