Stock is 4.10 ratio. If you went to a 37” tire The correct ratio to match stock would be 4.30, if you wanted a little lower than stock ratio for better acceleration then 4.56 gears would help turn the bigger tires. In reality with the 10 speed automatic trans there are enough ratios in the trans that a gear change for 37” tires shouldn’t make a huge difference unless it’s struggling to get going in first gear. If you had a non Raptor F-150 with 3.55 ratio and went to 37” tires then the gear change would make a more dramatic difference. Back in the day with a 3-4 speed automatic or manual trans the gear changes were more imperative to try and get your highway RPM in check, on these trucks the truck might decide to stay in 9th gear instead of 10th more often.
I don’t have the Raptor I ordered yet, but from what I understand the best performance mods would be a larger intercooler, a good tune, and CAI/exhaust. I think for many the engine performance is fine and they spend their mod money on suspension and lights like I plan on doing.