I play harmonica in The Sunny Day Blues blues band, so get through quite a few harps, I always use Lee Oskar's or Hohner Special 20's.
Over the years I have tried many different and more expensive makes and models including those with stainless steel reeds, valved, wooden combs etc. and I've been dissapointed with the performance compared to the above two models.
My choice or recommendations are always one of the above. They are both loud, good tone, and fast response, and I find both these models, notes are easier to bend.
I would recommend either of them, both for beginners or professional players. They are in my opinion the best value for money. Replacement reed plates are readily available for Lee Oskar's so are a little more economical, although, in the key of A, the special 20 tends to last a little longer before fatigue.