I own both and would rate the Bad Monkey the better value but the Tone Driver the more versatile pedal. The Monk also has a warmer and more natural tone, which is great if that's the particular tone you're looking for. It's designed to give a reasonable facsimile of an overdriven tube amp, and it does that very well. The separate bass and treble controls add a nice dimension of adjustability that most basic overdrive pedals don't have. It's an outstanding blues pedal, in particular, though it will do classic overdriven rock tones quite well, also.
The Tone Driver's "morph" pedal is definitely a cool feature, since it gives you the ability to change the basic character of the overdriven tone, and features emulations of three classic OD pedals--the DOD 250, and the Ibanez Tube Screamer TS-9 and TS-808 models. You can get additional "hybrid" tones by positioning the morph control between these three settings. The only thing I don't like as much with the Tone Driver is that I find its output to be somewhat less natural sounding than the Bad Monkey or other analog OD pedals. I assume this is attributable to its digital technology. But if you're looking for a pedal that will do a broad range of overdrive tones at an extremely reasonable price point, it's a very good choice.
BTW, if you want to save a few bucks, check out these pedals on eBay. I got both of mine that way, used but in good condition, and paid less in total than you would for the Tone Driver new....