For tracking blood pressure, Omron seems to be the go-to brand for both healthcare professionals and ordinary people. I feel that tracking blood pressure, should be relevant over time, even for athletes in good health. I also feel that it’s really nice to track all health metrics in one place.
Omron has support for their Connect App for many of their models, it already syncs with Apple or Google Health, so this should be an quick and easy integration for you.