Definitely get what you want. Both the 35 and the 37 trucks look great. From a "performance" perspective the 35 truck has an inch more of wheel travel, also better acceleration just by nature of less rotating mass. Likely a little better handling with a 35 than a 37 on road as well. 37 has an inch better ground clearance and the shocks are tuned to the 37 from the factory with a larger shaft to handle the load. Spare fits under the truck etc. If you want 37's and the cost isn't a factor then grab you one if you can find it. If you're just contemplating an order now, you may have trouble finding a dealer with any allocations left. If you find a dealer with remaining allocations it will very likely be even harder to find 37 allocations. Then if you did get a 37 allocation, it will likely be a much longer wait for production, delivery, etc. There are dealer orders out there for sale with ridiculous ADM's especially for 37's.
I saw a black 21 37 package at my dealer when I ordered my 22. Sat inside, in person the blue Recaro's actually look great and premium and I am a guy that only does black interior on my vehicles. The 37 stock wheels I think look really nice if you're staying stock. To be honest at first glance I wasn't sure if it was a 37 or 35, knew simply because of the wheels but was a little surprised that it didn't look a little more obvious in stock form. Still looked great of course and probably more obvious if side by side with a 35. I'm into an 800A with torsen and convenience package for $68,500(before tax,tag) a 37 would have run me $82k@ MSRP and who knows depending on dealers that are marking up. I love that 37 is an option from the factory. I just felt that at that price point I should be getting a little more actual performance. We shall see what the R brings and if any of us can get our hands on one. I am not interested in paying any mark up so I'll probably not get a hold of one. Good luck and know that no matter what you choose you will have a badass truck. I have loved every generation of the Raptor and finally have one coming...