These are the best small cap alts that I know:

BlockV - Great team and advisors, working project, lots of developers on board, low market cap.
Bomb - Experimental, lots of hype, first hyper-deflationary coin, low market cap.
Divi Project - Working project, great team and advisors, constant updates, low market cap.
Grin - First "mimble-wimble" ultra-private coin.  All sound fundamentals and low market cap.