I had a cheap pedometer from one of the supermarket chains, which I kept accidentally resetting, then after 1 1/2 weeks it fell off my belt once too often and stopped working.
This one is secure, has all of the basic functions - step counter, distance in miles or Km, Calories, and total time. I don't use the latter two, but they may be useful depending on your exercise regime. Resetting is done by holding both buttons for 2 seconds, so unlikely to do accidentally, and as well as being secure on the belt or waistband, it also has a security lanyard as well - so I have great confidence that this one will last a long time.
If you don't want anything fancy, then I thoroughly recommend this as it's easy to set up, and works well.
All well until the security clip (cheap plastic) broke, and of course it was soon after that the pedometer slipped off and was lost :(
Next time, I'll go for one I can carry rather than clip on.