It could be both, depends on your specifications on how you put your venture with but definitely I would go to BTC hence this is the buy zone of bitcoin right now due to bad market sentiments. Some altcoins are worth it too, any top 10 on CMC is nice to buy and hold too.

My take is nothing beats Bitcoin as far as investment goes specially if you are willing to invest money that you can afford to lose and then you will be a long term holder. And this is the right time to buy since the price is still very cheap. And just imagine if in the next bull run, the price goes to like 6 digits.

But as far as risk goes, meaning more risk bigger reward, then there could be few altcoins that could be good as a investment, maybe a few ETH or BNB or ADA will do for you. But there could be more riskier, and there could be element of what we call pump and dump.

Depends on how you look at it,

Are you for the long haul? meaning you are willing to buy that amount and not touch it till the next bull run around 2024-2025?

Or if you are short term investors then better look for altcoin in my opinion. Not sure how you can look at promising altcoins though because they are very hard to spot in the beginning unless you got lucky.