Well VHO can refer to T12 fluorescents, or T5ho that are overdriven (run at a higher wattage). The "T" refers to the diameter of the bulb. T5 are 5/8" dia, and T12 are 12/8" dia (1.5").
T5ho are the way to go IMO. Using good bulbs, and having individual reflectors will allow you to keep whatever you want. What size tank do you have?
-Justin