I tried playing on some Valve servers for the first time in what must of been 2-3 years to do some pyro contracts
There's lots of shots not registering and all sorts of wacky shit going on with the netcode on those servers. I've never had any problems similar to that on Skial servers leading me to believe Valve runs some cheap servers
Valve servers also feel really depressing to me. People rarely talk and there's no sense of community there.
I know most people don't hop into games to make friends but I've been playing TF2 since 2008, the sense of community grows on you making it hard to play on Valve servers after so many years of playing community servers