I've used copilot 5 for about two years, iGO my way 2006 for about two months and Tom Tom for about a month. Of these, iGo is clearly the best IMHO. It's route calculation is the least illogical. It is the prettiest and most user friendly, fastest in getting a GPS fix, and is the only one that warns (audio warning) me when I exceed legal speed limit. Tom Tom only display the speeding visually, but who could keep an eye on the device to know that while driving?
The real downside is that iGO can't run in 96 or 128 dpi mode whereas TT can. Of these, I personally think TT's route calculatin is the least sensible. I often have two of them running side by side (on two devices of course) to see the difference.
Now, i've decided to stick with iGO despite the display problem. I'm love 128 dpi, but whenever I use iGO, I just switch back to 192. Not a real problem if you do it while walking to your car. By the time I start the engine, it is reset back to 192 and gps ready to go.