I'm lazy so I bought a computer from someone that built it themselves. Was cheap and haven't had a single issue with it and have owned for 3 years now
Good choice on the 144 hz monitor, it's worth imo. I have an i7-4790k for my CPU and an old gtx 980 ti sc for my GPU that still runs every game I play more than well enough. 32 gb of ram and an ssd.
Looks like ur build is going to be solid. I'd bump it up to 32 gb of ram but other than that you should be golden.
Even though I agree with not going pre-built (from a retailer) I've always wanted one of those Corsair One's. They're pretty expensive but if I was forced to buy a pre-built that'd be it.