Actually those systems are pretty good. Was there something specific that is different than those? A genre?
Here are my suggestions:
Basic Role Playing is a d100 skill-based classless system. Mythras is based on it. BRP however is easier to get into in terms of rules crunch.
Open d6 (they have space, fantasy subsets). Again skill-based and classless though it does have ‘professions’ that focus on specific skill group. Star Wars d6 (West End Games) is the original system.
DND 3.5 and Pathfinder 1E have about 90% as open source, if you prefer d20.
Several hacks of Apocalypse World (powered by the apocalypse or PBTA) are free. Story/narrative based system. Extremely easy to get into. BUT you need a group of storytellers that wish to collaborate.
FATE is good but again, even more than PBTA it requires a group of active story-tellers.