I have the Bodylink. My wife has the A3 and I have used it. I would take the Bodylink over the A3 because the Bodylink registers splits with average HR within each split. The A3 has no splits at all. In fact, it has no real stopwatch function. The Bodylink also has indiglo nightlight which is key for my winter runs after work.
I think the Bodylink is more appropriately compared to the S120, which I have not used. I’m not sure about the nightlight on the S120.
I can say that the Bodylink is MUCH more intuitive for me after having a Timex Ironman watch for years. The A3 is still a mystery to me when I use it. The S120 may be easier - I don’t know.
Also, I have used the A3 and the Bodylink at the same time as a test. I got the exact same readings at all times with both.
Better brand than Polar, I don’t really know, all I’ve owned is polar.
The S-120 is very easy to use, that is what I use now. Any HRM will be easy to use once you have been using it for a while.
I believe anything above the S-120 has too many bells and whistles. I feel the important features are ave HR and split times. It would be great to have the bike functions, uplink functions and all kinds of stored memory but I don’t think it’s necessary. If I came across a great price on one of those models I would jump on it.
My bodylink has been unreliable, but the Timex customer service has been decent. Overall, I would have been better off either keeping my A3 or getting the S120.
I’ve only used polar HRMs (my 210 and wife A5) so I can’t comment on others.
I like the 210 much better then the A5. I find it easier to use and it has a 3 line display vs the 2 lines of the A5 so you can see more info.
If you can afford to spend a little more I think the 210 is a nice jump from the 120. You get a backlight so you can see in dark/dim areas and you get more interval features, otherwise go with the 120 over the Ax series.