I've never tried the watch, but I do use the Clear Blue Easy Monitor and Clear Blue digital OPK's and they work great! You use the monitor in the morning and it's a bit pricey. The only down side is that surges usually always shows up in the afternoon (from what I've been reading online) and my monitor doesn't pick it up until the next morning. So...I use the OPK's in the afternoon along with the monitor in the morning. That may seem a bit drastic, but it's what you do when you've been TTC for as long as I have and have known issues!
You could probably be very successful with one or the other! Hope that helps!