BTC and ETH , and that's it
$30k is not a small amount, you can get more than 1BTC.
Investing in BTC will never make you lost moroever if you are investing for long term investment. If I were you, I will buy 1BTC. And let the least to buy altcoins. 50% of the least for Ethereum, and others for BNB and SOL. I love those altcoins because I think that they are very potential compared to any other cryptocurrencies. But, this is only an opinion, it is better for you to think more and cosnider what best and most suitable for you, related to your investment target.
And basing from the previous success, those mentioned assets can bring a decent amount of profits, fair enough for long-term holding
if you are not into a quick to rich type of investment, you can buy and hold those coins till it reached the target profits that you will setup,
for the meantime, after buying better, to stay away from the market. In case you are really into passive side, monitoring the market might
shake you, a lot of fluctuation without concrete plans you might lose instead of earning from your invested amount, $30K is not a small
amount better to make sure that you are mentally and financially aware of how the business works.