I'm working on this from the day the tire sizes were announced.
I'm in Northeast so the snow performance is important. At the same time, I do not see that swapping to winter tires is necessary in where I live (MA).
Another consideration is speedometer error. I would like to keep it as small as possible.
So far 265/45-R20 replacement for myself I narrowed it down to the following 2:
Michelin Defender LTX M/S in 265/50-R20 107T - great overall tire, good wet and snow traction
Continental TerrainContact A/T in 265/50-R20 107T - a bit more off-road oriented with still good on-road performance
The speed rating in both of them a little lower (118mph) but still acceptable.
These two options do not give much increase in the sidewall (~0.2 inch increase) but also do not through off the speedometer. If much thicker sidewall is needed, I would consider changing the rims to 18 inch.