What metrics do you like to track other than calories?

Weight, calorie intake and basically just carbs because I feel miserable if I don't have enough. Plus my sports watch tracks a lot of interesting stuff. The most interesting for me is heart rate variation as it's a great metric when coming down with a cold/covid/other stuff before actually feeling sick, and a great metric for showing how I heal after accident or surgery.

I have daily minimums for protein grams, fat grams, and fruit/veggie servings (I'm OK with the rare off day, but aim to hit those on the overwhelming majority of days. I don't "track them", other than logging as I go through the day and striving to hit/exceed them. I try to make sure I get MUFA and PUFA, not just saturated fats, but don't have a numeric goal.

I weigh myself every morning (unless away from home), and log my weight and estimated body fat percent in Libra.

I use a Garmin tracker to record my workouts, and log workouts in MFP (not necessarily using the Garmin's calorie estimate, if I have a better one). Sometimes I run reports in Garmin Connect to look at long-term exercise totals and trends, but I care more about how my body feels and performs than about the numbers or how I look.

I don't track it in the sense of recording it in some structured way, but I watch my on-water rowing splits (time per 500 meters) on speed/power pieces and strive for progress. I log some stats about my machine rowing in a notebook. When I strength train (seasonal at best, not consistent), I write my exercises, sets, weight and sometimes other notes in a notebook.

I like data, but I don't usually have goals about the numbers, other than wanting to keep my weight in a certain range. The data is there to serve my real-life goals, like being healthy, improving technically in my sport(s), and things like that. The data for it's own sake? Not really.