Which bulb do you prefer to use for a basking light for aquatic turtles?

Just as the title states, what kind of bulb do you use for a basking light?

I just picked up a 20 long at the Petco sale and am going to do a turtle tank for an RES (this will be my third time keeping turtles, it's always been a fun adventure...they have a friend's approximately 20,000 gallon clay pond to move into when they outgrow it).

Right now I have one of these bulbs:
http://www.amazon.com/48690-100-Watt-Reveal-Bulbs-4-Pack/dp/B000089DC9

Which provides plenty of heat, being incandescent, but I will have to look into something better soon, and would appreciate any suggestions.

So maybe the 100 watt Reveal bulb will be ok after all? It's not true full spectrum, but it's a pleasing light, much more so than "soft white" or "warm white" bulbs, which are too yellow.

I am planning on running a fluorescent light, probably ReptiSun...unless I can find a cheaper bulb that works just as well. A ReptiSun bulb is what I used last time (over 5 years ago) not sure if there is anything else out there by now.