forerunner 265 - I've used it for running triathlons and marathons and have had no issues. Garmin has great automated training plans where you can upload various races you're preparing for and Garmin will schedule your runs so that you can meet your time goals. Also highly recommend the vibrating metronome feature to improve your cadence. This feature has dramatically reduced the number of injuries I get. I don't use it to track gym workouts (e.g. lifting). There is a feature for that but I haven't tried it. If you want to really nerd out on your running the HRM Pro Plus provides amazing running dynamics information which again is very helpful for improving running form and reducing injuries.

For women you may want to look at the forerunner 265S which is identical to the forerunner 265 but is slightly smaller. The HRM-fit I believe gives the same data as the HRM Pro Plus but is designed to fit under a sports bra