if you think a PWD and a BC might be too much dog for you, I wouldn't bother looking at Malinois - while there may be a soft, mellow one in ONE class, in general that is not the norm for the breed and that dog is an abnormality and quite rare within the breed. Mals are BC's on crack.
along that thread, while engies are cute, english cockers are not performance dogs in the normal sense. They are quite happy to be couch potatoes and none of the ones I have met have a ton of drive - they are lovely sweet dogs, but they would be on the opposite ends of the Mal spectrum. They are definitely reliable off leash, get along great with everyone and everything - but working them isn't always a top priority with most breeders, so they aren't really looking for those temperaments. I know a few people doing some obedience and more doing agility, but they are still few and far between.
I know quite a few nice brittanys in the obedience world - some are a little crazy, but all work like little fiends and are great dogs to be around.
Another breed to consider would be a welsh springer, or a regular springer. ESS's can be a little more dominant, but welshies are much more laid back.
a Golden would be larger than your size requirement, wouldnt it? youd have an easy time finding a golden to fit your requirements .
i would also second the toller, or a PWD. I don't consider them nearly as dominant or pushy as some other dogs, and if thats the breed you want, why wait?