probably on that average for 2 years it would be bitcoin that can guarantee a good return IMO. indeed it's been how many times trying to break the current ATH in the last bull run so it's expected to improve more in the future..
When it comes solana i don't have trust because they're stuck up till now and seems keep losing interest from big investors. So its quite skeptical to trust especially in the long long run.
Only bitcoin alone? What about solana and ethereum? All of them are actually good for long term especially eth as the merge has already done. People are expecting a big growth from its price. For solana, it is stuck because we are still in a bear market and as you can see, other coins are also on the same situation but wait till the bear ends and you will see that they will race towards their new all time high.
BTC is definitely going to be the first on this race and then followed by eth. Can't say if sol will be the third because there are similar projects who are like sol but one thing is for sure and that is sol will show a significant increase.