I've not tried the other but Strava has made me push a little out of my comfort zone. I'm sort of a plodder so it encourages me to actually put some effort in, which has resulted in a little improvement in my speed. It would always be safety first, there is always another day.
Plus it encourages you to look around, perhaps go somewhere else than you have been before. You can see progress which I hadn't noticed before. And I was interested to see I managed to equal one of my QOM's this year without realising at the time, so it wasn't a one off fluke. I rarely go out looking to beat a segment, though I did the other day when I realised I was going to have the wind behind me, it meant I had something positive that day when the rest of the commute was hard work.