There's no semi-competitive mens only league that I know of, yet if you find one please let me know.
Metro @ the Oval is very competitive, same with the Kings league downtown. You're better off joining a co-ed league.
I play in the Kerrisdale basketball league. It has 2-3 tiers depending on the season. The top tier is very competitive, the bottom tier is hit or miss and might be more of what you're looking for.
I also play Urban rec at the Oval. I'd say its more hit and miss than the Kerrisdale league. There are a few very good teams that would be top tier in the Kerrisdale league (the team leading the standings has a couple players on the Metro championship team), and a few teams that seem like they've never played basketball before.