I had asked a few hours ago about a second display, and before I forget where I was going with that let me throw some thoughts out there for you, as I’m gearing up to be away from my desk for a bit now.
So if you do NOT have a second display, what you need isn’t necessarily an ultrawide display but rather a very nice display, in the 24 or 27" range, to get the most out of your gaming. If you get a 27" display, I recommend 1440p. If space/budget is more of an issue, stick with 24" at 1080p. I don’t think 1080 looks great at 27" or above, but that’s just my opinion.
And to go a step further, since you have an Nvidia card, you will want something with Gsync and a really nice IPS panel to really blow your socks off. The nice thing about a great monitor, is it’s one of those upgrades that can last years and years so it’s a great investment.
If you want to stick with 1080p, which your 1060 can drive very well indeed of course, I would look at this one instead of an ultrawide, and keep the 21" as a secondary display - something you can browse the web, have netflix open, steam chat, or etc. while you game on your primary display.
https://www.amazon.com/PG248Q-G-SYNC-eSports-Gaming-Monitor/dp/B01M4II4M4/ref=sr_1_1?ie=UTF8&qid=1508361610&sr=8-1&keywords=pg248q&th=1
I don’t see any 24" 1080p displays with Gync that feature IPS, which is a shame, but I believe this will be a fantastic display all the same.
If you want to try your hand at 27", I believe strongly that 1440p is the ideal PC use resolution - none of the 4K jank some applications/games like to have, works great for everything from watchying videos/movies to browsing the web, and 27" is a near perfect size.
The 27" display I’m looking to buy is right here:
https://www.amazon.com/dp/B017EVR2VM/_encoding=UTF8?coliid=I2QN5IGCZYOGAC&colid=3F7F3MZ299QNQ
So maybe ask yourself what you are really looking to get out of your gaming/PC time and go from there?