Best 27" Monitor
It's really all in the question title. I'm looking for a new monitor to my make beautiful games look even more so, preferably 27" my current one is 24". Also is 120hz worth it or not?
Higher refresh rates are more desirable for FPS. What kind of resolution do you want and what price range fits for you?
120Hz monitors will make for smoother looking movements on your screen. A lot of people suggest that you should strive for 60+fps to take full advantage of the higher refresh rate.
120Hz is amazing (I have one), but is currently limited to 1920x1080, which I personally wouldn't want in a 27" monitor (I would want a higher resolution, and thus smaller pixel size). Furthermore, unless you attempt to overclock the monitor, you will be limited to TN displays.
Is your primary interest color, black levels, viewing angles, etc. or in very smooth movement and higher framerates?
Assuming your in the UK, a good 27" 1440p monitor with HDMI would be http://uk.pcpartpicker.com/part/dell-monitor-u2713hm . It is slightly above your price range, but most 1440p and above monitors from established manufacturers are even more (maybe excepting sales). http://uk.pcpartpicker.com/part/asus-monitor-pb278q would also be a good choice, though it is slightly more expensive than the Dell. Both are of course limited to 60Hz.
If you are willing to step down to a 24" (which it seems you would need to do in order to stay in you budget), a lot more options open up to you. The majority of 120Hz (and 144Hz) monitors are in this size range as well as a lot of other good options.
With a GTX 770 I would strongly recommend going with a better resolution (or higher definition) than 1080p and upgrading to 2560x1440 (1440p).
You can get some very affordable 1440p displays and some of them can be overclocked to to 120Hz, giving you the best of both worlds (1440p AND 120Hz). Gaming in 1440p will ruin 1080p for you the same way 1080p ruined your old 480i TV.
The Qnix is an example of a 1440p monitor that can be OC'd to 120Hz for 350$ and is the best bang for your buck you can get.
If you do get the Qnix with the intention of OC'ing it be careful! there are TWO models with the same name!! You want the one with single input, the "bypass" model as the other one CANNOT be OC'd.
Hope this helps,
cookiebiscuit has a point, especially since you have an nVidia card. However, if you don't want to wait for G-Sync monitors to come out, you could get a current monitor, and later add a module to enable G-Sync whenever they come out. Current ones that are good and in your price range are:
http://uk.pcpartpicker.com/part/asus-monitor-vg248qe - Glossy
http://uk.pcpartpicker.com/part/benq-monitor-xl2420te - Matte
http://uk.pcpartpicker.com/part/benq-monitor-xl2411t - Matte and the least expensive
http://uk.pcpartpicker.com/part/benq-monitor-xl2420tx - Matte, and also the most expensive (slightly out of your budget), though it comes with 3D-Vision glasses and an embedded IR emitter for 3D-Vision (What I have. It works well.) You would be able to use the 3D capability due your nVidia card. Also is one of the few 120Hz 3D monitors that can also be used with 3D over HDMI.
If you go with Pete_the_Puma's route, be aware that Qnix is a Korean brand (maybe questionable quality) and is very limited. (Only DVI) Furthermore, while many of the limited Korean 27" 1440p monitors can be overclocked to 120Hz, some can't reach that high. It depends on the individual panel. There may also be some strange customs costs, seeing as your in the UK.
Easy to understand article on these (similar) Korean 27" 1440p monitors: http://www.rockpapershotgun.com/2012/08/24/hard-choices-the-200300-2560x1440-27-monitor/
Qnix would probably be less risky than the eBay brands talked about in the article, but beware that you would be taking a risk if you chose it.
Quote from the article 722C posted that sums up my feelings:
"The only problem I face is that using a smaller/low-res monitor ever again will likely prove extremely frustrating after such glory."
Sure there is SOME risk involved, but getting the screen through Amazon I believe offers additional insurance/protection. I ordered one from Korea through eBay and the process was a breeze, the monitor is phenomenal.
For the Qnix, quality is subjective, the panel is made by Samsung, so no complaints there. Where quality is obviously lacking is stuff like the stand, which is super wobbly and has no adjustments, but it does the job. It also has crap speakers, but I don't think anyone actually uses monitor speakers. For me, its pretty much the perfect monitor. Cheap, 1440p, excellent colours, 96Hz, input lag of a TN display thanks to single input.
Ordering from Korea is pretty stressy though, if you get a bad one they take it back but it would be a headache.