I built my own mount using the belt holster that came with an Otterbox Defender case and a spare windshield clamp. Basically just drilled a couple holes in the holster and bolted it to the mount with some spacers. Had it mounted right in the centre of the front rollbar tube but just moved it today to the left, directly above and in front of my head. The phone is my old LG G3 that I mainly use just as a trip tracker to record my trails for looking back on later, so it never leaves the mount until I get home, but it works well up there and never moves as the phone clips solidly into the holster. I had another of the same holster mounted to both my four wheeler and snowmobile for similar purposes and never had an issue.
I didn't usually spend any time looking at it while driving when it was in the centre as it was kinda awkward to look up and over but where I have it mounted now I think will be much easier to see at a glance if I want to use it for any kind of navigation or something like that.