You need to specify further. What do you mean by a low market cap altcoin? Do you mean alts which are having $1 billion? Or those having market cap of less than $100 million? I would consider an altcoin as a low market cap coin, only of the market cap is less than $1 million. There are a few promising ones in this category (provided that the development continues without any issues), such as Veil, DeepOnion and eBitcoin.