I'm sure you'll post here if/when you come across something that sits well with the Dell!
I put my AOC Q2770P on the desk along with the Dell when I was setting it up, and I could not live with the huge difference in bezels long term!
27" 4k IPS come up cheap regularly...the orange buyer site had an Acer for £249 recently...! LG panel, friend has one and rates it highly, freesync works 40-60 without issue unlike LG branded models that only seem happy with 48-60.
Am loving my Dell TN, though...! My brother who plays CSGO competitively/ranked/whatever didn't believe that it was a TN as the shift is so subtle compared to other TN panels, and the colour is so much better.