4k is awesome
144hz is awesome
4k+144hz is super awesome, although quite expensive still, when compared to other 144hz or 4k products
I remember paying close to 3000$ for Apple Cinema 30" back in around 2005, with 200$ student discount. That actually gave me a competitive advantage back in a day. (and it still in service as a matter of fact, which is quite impressive)
This isn't a case with current breed of 4k 144hz though (even though I like it quite a lot)
If was made to chose, I would go 4k over 144hz. Difference between 1440p or 4k or alike is quite dramatic.
144hz is nice (really nice) in fast paced games, but 4k is better in most all other applications.