Always tricky. For example, I loved RQ for Glorantha, but looking back was not a fan of the system at all.
James Bond RPG - The first RPG that nailed the genre is was supposed to portray. The Q Manual and Thrilling Locations are still two of the best RPG supplements ever.
Prince Valiant - Greg Stafford came up with one of the best absolute beginner RPG system-wise. Unfortunately, it was tied to a very niche license and it didn't get the exposure it deserved.
Dying Earth RPG - Never played it, but really would love to with the right group.