From what I've played of both Session sucks, the animations/physics are stale af and too capped in. I've been playing Skater XL since the first beta build (Steam Early Access) and even the first beta build had better physics than Session. Skater XL's mod community is way better too, I'll admit though Skater XL is trash on console or vanilla on PC. The game is great when you have it modded and it's primary mods that make it better in fact everything you complained about can be fixed with mods...
1: Graphics - With Reshade & XL Graphics Mod combined you can actually make the graphics look better than Session and more atmospheric...
Note: This isn't even the best graphics config, it's just what my computer can handle (Ultra Settings with Reshade & XL Graphics) but you can make it look even better if you have a better system.
2: Customization - Due the mod community there are thousands of customization options personally I have exactly 2110 customization options which include everything from shirts, pants, hats, decks, trucks, wheels, etc. from pretty much every Skate Brand in the book -
https://skaterxl.mod.io/?filter=t&tag%5B%5D=Gear There's a mod to be able to change the shape and size of your deck & wheels. -
https://skaterxl.mod.io/board-utilities& There's also a Gear mod that has things such as facial hairs, different hat models, Apple Earpods, glasses, blunt, cigarette etc. -
https://skaterxl.mod.io/gear-utils3: Gameplay Elements - Mod wise you can play Multiplayer, play games of Skate Dice etc -
https://skaterxl.mod.io/xl-multiplayer ,
https://skaterxl.mod.io/skate-dice5: Player Model - looking at both Skater XL's player model is actually more superior, it's just the default skins that make it look less superior. I personally made a Skin Pack that fixes this -
https://skaterxl.mod.io/xxlskinpackDefault Skin...
Custom Skin...
It's also worth mentioning the custom maps for Skater XL are 1000x better, and now you don't have to model them from the ground up and put in all the grind splines. You can download blank/empty maps & using the Map Editor mod you can create your own in game plus there are tons of options to use and more and more dlc's for the Map Editor are being made to give you more options. Also worth mentioning you can edit any map and spawn objects to skate then save it so you skate your DIY spots later -
https://skaterxl.mod.io/map-editor