I think the Xbox form factor is fine. I've used DualShock 3 and 4 a lot, also Joycons and Steam Deck, but I don't mind the different layout. The ergonomics are good. Better than Joycons and maybe even the DualShock. I haven't used DualSense though. The Steam Deck is superior for me, because I always use the right track pad, since it's much better for controlling the view than a joystick is. Maybe I'll try to get a Steam Controller sometime, but till then I am completely satisfied with KingKong 2 Pro.
Steam controller is great for that, I love it but the build quality doesn't feel good, it's quite light and plastic-ey
If you like the track pads on the deck the ones on the sc are very similar you'll probably like those too. The joystick on the sc isn't the best though and it doesn't have a right stick so kinda sucks for games designed for twin stick
I preferred Xbox form factor over the Dualshock 3 and 4, but Dualsense is just next level in terms of ergonomics. I am not sure if its just me, but it feels molded to my hands and presses into my palms in all the right places. I just wish it had an easily replaceable battery pack. I miss the AA batteries the Xbox controllers used.
I use it wirelessly with my Linux PC and Nintendo Switch. The latency is completely fine - I don't have any problems with it. Yes, the buttons are dampened, the loudness never bothered me. Overall, I am satisfied with my choice.