What features do you want in a HUD? Are you JUST looking for the statistical display to layover the table or do you want to use the HUD database for analysis? If yes on analysis - how sophisticated?
DriveHud - easy to use, beautiful, drag-n-drop configuration, light-weight reporting
PokerTracker4 - easy to use, highly configurable, robust reporting
Most HUDs have 30 day trials. Install a few and try them out.
For free still are FPDB - free poker Database is and PokerStoker in web. Good to micro and low limits.
Very good with monthly prize is Jivaro, but this hud is only to PokerStars.
change instances of free poker into a link to https://www.cardschat.com/strategy/free-online-poker-game/