If you are going to stick with the 3k changes, don't bother with Mobil 1. You are throwing money out the window if you do.
We haven't seen how well the Mobil 1 0w-20 holds up yet. The motorcraft 5w20 has shown itself very well in short intervals (3000 - 4000 miles)in engines ranging from the 4.6l V8, the 5.4l V8, the 6.8l V10, and the 5.4l Supercharged V8 in a Lightning.
Based on Mobil 1's performance in other weights, I'm sure the 0w20 will hold up fine and I'd be comfortable with a 5,000 mile interval (which is likely the normal service interval recommended by Ford).
Either will do fine - just decide if you will keep doing 3k changes. If so, stick with the Motorcraft. If you want longer, then I;d consider the M1.
FWIW, I am running 5w20 in both my F150's - one with 160,600 miles on it and the other with 85,000 on it. Both ran 5w30 until last month. Neither has shown any consumption issues to date - and it has been upper 80's - low 90's most of the time.