Rolisteam was very popular in the pre-roll-20 era, let's say 2008-2012, I used it a lot at the time, it was way easier to use than maptool.

it still has the essential function for a VTT : share a whiteboard or a map, move a token on-it, have common and private text-chat, roll dices However, it's a bit more complex to set-up than a centralized app (open some port on your router), the character sheet manager is complex (not that it's easy on roll-20 but you'll find sheet for most games)