I think asking which coin is best to trade looking at their volatility level is the wrong question, since the crypto currency market is overly dynamic, nothing remains the same permanently, and this is for us to know that, a coin that is volatile today may be relatively stable tomorrow, making it no longer a good choice for traders to trade on.
I think what is more or most important is not to know the coin that is volatile to trade, but to know how to professionally trade very well in a market that is volatile, for when a supposed trader knows how to trade in a volatile market, he or she can be able to find good opportunities in other coins that are volatile as well; to trade, so that the day Sol, Avax or any other mentioned coin here is not volatile, the trader doesn't end up stranded.