The reptisun 10.0 is the stronger bulb, and one of the most tested and reliable flourescent tube UVB bulbs available around here. The reptisun 5.0 is decent, but not as strong, so if you can get the 10.0 go for it.
Also, make sure you're getting the long flourescent tube version, not the coiled or compact bulb.
There are a variety of problems with the compact bulbs of any brand. Some cause eye problems with dragons, others have a dangerous inital burn in (they put off dangerously high levels of UVB for the first couple of days). They also tend to have an erratic/fast decay rate, so that you're not quite sure when they stop putting out enough UVB for your dragon. Unless you have a UVB meter to monitor the UVB being put out by the bulb I wouldn't risk a compact bulb, there have been too many reports of dragons suffering under them. The flourescent tubes on the other hand, don't pose any of those risks and have been well tested and proven to be reliable sources of UVB for your dragon.
wow didnt no that thanks alot for your help now i will definitly get the flouresecent bulb , im greatfulll that there is people like u that can point out my soon to be mistakes , thankx again