Most altimeter watches I have used work well when you reset them occasionally. Yours doesn't sound above average to me but par for the course. You're basically matching you're clunky wording. Saying it doesn't work perfectly so I have to reset it every once in a while to make sure it isn't too wrong.
That being said I don't know that I would recommend any watch over another. I would think a reasonable quality brand name would be wise. Then start using it and get a sense for accuracy. For me a lot of times you can use relative altitude just as easily as absolute altitude for navigation purposes, e.g., go downhill 200ft to the CP. Therefore the altimeter could say anything as long as it can accurately measure the change over those 200ft which most (all?) altimeters will do well. Absolute accuracy is always preferable but as has been stated there doesn't seem to be anything yet that can do it without some degree of error and drift.
I have had some garmin GPS watches and have seen varying results on their ability to estimate total elevation change on a run/ride. I don't know if that correlates to the quality of altimeter readings at specific points or not.
It appears there are different settings on how the autocalibration is performed on Garmin watches. I don't have this option on mine. I used manual calibration during the race this weekend to make occasional updates.https://support.garmin.com/en-US/?faq=FhOYuggxmV6A...
It may not update during any activity (AR or not).