I personally prefer using top tube bags which keep the phone securely mounted inside, but full access to the phone is available through the thin plastic lid. It also has room for me to put things like keys, wallet, spare phone battery/charger, etc. I've used handlebar mounted phone holders before but after my phone fell out of it (luckily no damage) I decided I wanted something better. And looking down at my top tube just behind the handlebar stem is not that much of a distraction compared to looking at my handlebars. Plus I know if I wreck my bike my phone isn't going to go flying off somewhere.