Good routings - all of them.

If upgrade success is your top priority, I would avoid FRA. It's tough even on for a 1K on high fares. I would avoid FRA at any cost, especially because if you fail the upgrade, you are stuck in the body of the abominable 744.

I never ever missed an ug ex LHR or ex AMS, even though AMS-ORD can get a bit heavy.

I would stick with LHR - decent plane if you loose the ug and excellent chances to make it.

You realise that when waitlisting for an upgrade with miles as a 1P, you will be stuck in the PB waitlist. If you can get SWUs from someone, you will be moved to the PA WL. Greatly increases early clearing of your upgrades.

Yes FRA offers the highest probability to end up in the new cabins. But remember that even FRA-SFO is far from certain to be 'held' in the new cabins. And with the new cabins comes the endless switch between seating configs, loss of seat assignment even last minute. It's really enervating.

I lost my assigned seat so far on every single new cabin operated flight - hate it.