obviously more light equals more bud, but its all about what you can afford, how much heat you can handle, and how big you want to go.
i can however tell you that length tube florescents are inefficient due to the shape they are made. if you are going to stick to flours and want something you can buy anywhere for cheap go with high wattage helical CFL's. Stores like wal-mart or target or whatever will have cfls in the range of 40 and 50 watts for 10 bucks or so.
but if you want massive buds then go with a 1000 watt HPS, i dont think they make them any more intense than that