Maxperson
Morkus from Orkus
This is one of those things that really has no good answer. If you reduce the casters, magic ceases to feel wondrous and magical due to its weakness. If you elevate martials, they cease to be martial abilities, because anything a fighter can do that rivals high level wizard spells is going to be supernatural(magical).Which is why a lot can be done to correct the imbalance. The real issue is the direction you want to go:
You either decrease the power of casters to bring them down to the martial level, or elevate the martials to bring them up to the casters. Or, try to find a happy medium between the two extremes...
Personally, I am for bringing casters down, many others want to elevate martials.