It really depends on what you want to keep in the tank. Money also has some to do with the choices. I keep softies and some LPS under my 265w PC lights. If you want to keep SPS or clams then you have to move up to MH. I know VHO throws some good light but I don't know much about them and cost.
Look in to what you want to keep and their lighting requirments and go from there. If I had to do it over again I would have gone bigger better but again money is sometimes an issue.
HTH
Tim