Please tell me what your favorite tracker is and why.

Hi, Barb, I'm about your age (66) but possibly more comfortable with technology (retired IT). I'm very happy with my Garmin, but I think I may have different priorities than yours for features. (I have a Vivoactive 3, now several years old. It seems to still be available, but the equivalent new model is the Vivoactive 4, I believe.)

In general, according to recent research, most good brands are good at heart rate, and pretty good at steps . . . but not very accurate at sleep tracking, and variable at calorie estimation. I suspect a piece of the calorie issue is that the devices rely on the same basic research as something like a web-based calorie calculator as a starting point, but then add on more personalized algorithms to estimate calories based on distance, arm movements, etc. They may be likely to be pretty close in all-day estimates for people who are close to average for their demographic, but can be off for some, not always for obvious reasons.

As a vast oversimplification, looking at the top tracker brands, it seems like athletes (even recreational ones) gravitate to Garmin, people strongly attached to the Apple ecosphere gravitate to the Apple watch (especially if smart watch features are important to them in addition to tracker features), and people who are more oriented to steps-based activity often gravitate to Fitbit (especially if their friend-group uses them). (Before anyone gets angry: Yes, very oversimplified, many individuals are exceptions, the devices themselves all do a lot of the same functions, etc.)

To me, of those, Fitbit has more options that are a bit more delicate in size or jewelry-like, if that matters to you. There are some new models, but the Garmins overall tend to have more of a sports-watch look. (There are starting to be brands like Bellabeat that are now being marketed to women as much more jewelry-looking, but I don't know much about them.)

If you've been happy with your Fitbit, and aren't too comfortable with technology, it might make sense to stay with the Fitbit line. It should be more similar to what you're used to, even if a new model.

I like my Garmin because my priorities relate to being a recreational athlete (on-water rower, as my main thing, but that's not all I do). My device does all of the things you mention, but has specialized statistics/estimates for different sports (including rowing, on-water or machine) that I like, plus Garmin integrates with a wide range of 3rd party sports applications. Because my eyesight isn't what it once was, and I'd worn a sports watch before getting a tracker, the large watch face (coupled with a large-font selectable default display) work really well for me. The device is very sturdy, and I'm pretty hard on it.
It has had no technical problems over the . . . 2-3 years? . . . I've had it. I've replaced the battery, but it still charges well, and charges quite quickly: Usually, if I put in on the charger when I hop in the shower, put it on after, it's well charged all the time, unless I do some super-long outdoor GPS tracking thing. The battery lasted a long time; I think I've only replaced it once.

For me, it's terrible at sleep tracking (not unusual, from what I read, for all devices; but I personally have some unusual sleep-cycle issues that may complicate it further). It's also not good at all day calories for me, but it does estimate in the ballpark with online calculators including MFP: Those also tend to be quite far off for me. (This suggests to me that I'm statistically unusual, not the the device is bad. The same brand/model seems to be reasonably accurate for others.)

I had a Fitbit for a few years but switched to Samsung Active 2. I have to say that after having my Samsung for almost 2 years, I like it much better than Fitbit. Of course, having a Samsung phone helps. 😏 Every Fitbit I had broke within a year and a half...

I switched from a Fitbit to an Apple Watch much better I was always having connection issues with my sense and my Apple Watch stays connected all the time