My first non D&D RPG was before playing D&D: Advanced Fighting Fantasy, a system based on the old "choose your own adventure" fighting fantasy book. It worked reasonably well but had some balancing issues.
Troika! , interestingly, is built on this system and has fixed most (but not all) of said issues. Troika! has a strong, zany flavor that some people love and others... not so much. But it would not be difficult to make it into a "generic fantasy" system. I think it would work great in warhammer.