Hi
If you are looking for a solid investment, go with Bitcoins but do realize that people with power , the big whales are trying to Manipulate the price and make the BTC fall down. Take example of musk and square they are now suddenly all about environment, when they do not realizing that soon after we will be done with all the BTC and then only power consumption would be of transaction confirmation, plus people are already looking for greener alternatives. So the price might go down but at the end it's more or so a long term investments.
For short while go for DOGE , Elon Musk is manipulating it's price also therefore the market is strong there right now but do not trust the man , take out when you make enough profit. Like you can literally buy at 0.30 and sell at 0.50 even then if you had a lot to invest you can get good profit. But I don't think it's worth considering for long term. Then we also have ETH. It's really good opportunity too. But BTC Gold....why ? Just why ?