Another recent convert to Strava here. Started out using the phone app but soon went with a Garmin - as long as you've got a laptop/PC/etc to upload the data to it's far better than using a phone. For Strava purposes a basic model is plenty good enough, or you can use a Forerunner watch, and lots of those can be picked up very cheaply indeed. I find Strava gives me motivation to go another couple of miles, push a bit harder up the hills, get out on days when you're in two minds about it, etc. And it's a great feeling after a good ride to know you've got the data to look up right afterwards as a little pat on the back to yourself.
It's also had the effect of getting me started on going running, which I've never really been interested in, and depressingly it turns out I'm a far better runner than I am a cyclist...