That's going to depend on:
- the ambient temperature of the room where the enclosure is/will be
- the heat-loss of the enclosure
- the output of any other bulbs or heat producing items in the enclosure
First let me ask why do you think you need one?
Would a hotter basking light do the trick?
If it's for nighttime, what's the nighttime ambient temperature of the room where the enclosure is/will be?
If we're talking about a glass walled terrarium type tank, have you considered insulating it? Half-inch rigid foam insulation (white, pink, or blue) works very well. Insulate the back, sides, and top (except where the lights and ventilation are). Assuming we're talking about a baby dragon, this is also a less expensive option for when you upgrade the enclosure when the BD gets larger in a few months.
Once the other question have been addressed, finding the best wattage is usually a matter of trial & error to get the temperatures in the tank right, i.e. you may have to buy more than one and settle on the one that does the job. The same trial & error applies to finding what wattage basking light works best.
As far as brands, I would check out the options someplace like Amazon, and look for large numbers of positive (5 star) reviews.