Cardano, XRP, Polygon. Apart from BTC of course. They are projects that have utility. You can invest 50% in BTC and the rest in all three coins. Polygon has a smooth transaction speed. XRP and Cardano are good coins because they are in the top spot on CMC and they are old projects which proves that they have good fundamentals.
I think that Ethereum is also good for investment. During the rise of the market Ethereum rise even more than Bitcoin.