I have the Maverick 733 and it works great. There may be better models, but they also cost a lot more. I agree with Peeps, get extra probes. I am waiting for them to go on sale and then buy a couple.
Terry - Learning more about Q every day...
Weber Smokey Mountain 22.5" - Weber Genesis S-330
Pitmaster IQ-120 - Thermapen - Maverick ET-733
For info on any mods I have done to my WSM, please see this post