Tophat, which is based on XCsoar but with a different user interface, is all about ergonomics. (Thank you Robert Dunning!) It shows you the arrival altitude at nearby airports and landable points, right on the moving map. And you can tap on any waypoint and then tap "go to" and it becomes your new destination that it guides you to. That's handy if you get low and need to divert towards a safe landing point. If you later want to resume the original task, tap the nav bar and then tap "resume task".

And if you want to edit the task and choose an arbitrary waypoint, you can have it order the waypoints by nearest distance to your current location, or by highest arrival altitude, or alphabetically.

And talking about ergonomics, you can choose the hardware device among many possible - just about anything that runs Android can run Tophat (or XCsoar). I use an old Nook e-reader because the screen is large (6 inches) and the contrast of the e-ink type screen is not affected by direct sunshine. I've arranged for it to communicate with the FLARM but that took some hardware hacking.

BTW the STF does not vary with the wind, unless it's a survival glide to a landing.