What are the most promising low market cap coins that are still under $1?
It doesn't really matter if a coin is under $1, because you must consider also the total supply of the coin. If a coin supply is 100 trillion, it will be under $1 even if its market capitalization is higher than Bitcoin's. You should be looking at market cap instead. It's still not a perfect measure of the coin's value, but it's as close as you get.
you got a very good point .total coin circulation is important in chosen a coin. I Will recommend him to look into RDD and SC