I am using my third one, I started using one several years ago and found it to be quite helpful when doctor was adjusting medication. I do not use it routinely anymore but do check several times in between doctor visits, when I'm feeling ill or when starting a new medication with a risk of elevating bp. As far as brand names, I don't know there is much of a difference--the one I'm using right now is a drugstore brand and it works fine. I am assuming, of course, we are talking about the digital type. I would advise buying one that use the femoral artery above the elbow as opposed to the wrist, I find that to be more reliable. One thing I would advise you to do is to take it along to the doctor on your next visit and compare it to their reading. The mercury type are much more accurate, I believe, but the digital should be somewhere within the "ballpark". What it does do is give your doctor info on trends and when taken several different times of the day, allows them to view the effectiveness of the drug you are taking.
I began using mine even before I began with the medication. For six months, I tried modifying my diet but that didn't do anything. I am not overwieght. I already exercise, so that wasn't the problem. I think for me it was two things -genetics and age. At first, I wanted to believe it was white coat hypertension but as time went on, I began to realize the seriousness of the situation of this elevated bp. Yes, andrew is correct about medications except when the benefits outweigh these risks. Sometimes the only alternative might be (after all-else fails) would be to ignore it but the consequences are life-threatening. Unfortunately, and this is part of why I was reluctant, once you start taking them, you will probably have to remain on them. The last I read about it was that even mild/moderate hypertension can cause damage and should be addressed.