Oh yes that Dell U2414H was fast both in response and lag for the time a bit ahead of its time in the category, so it's still up to date.
The updated version of it (U2417H
J) seems less interesting because of more 'glow', but the contrast is better as long as it's not watched too much off-angle.
There haven't been many reviews of 24" full-hd monitors lately, too bad NCX's wcg forums links are dead at the moment because he's listed most of the interesting ones with actual reviews.
__
Anyway, some replies with added info;
- size
21" monitors: that's a category that doesn't get any attention at all today unfortunately, 24" is the minimum size for which you'll find enough material
- resolution
1080p (1920x1080 aka Full-HD) is fine, getting one with a higher resolution like 1440p (2560x1440 aka WQHD) will open the doors to finer detailed, more realistic fancy features like CRT shaders that imitate old low resolution tube TVs and arcade monitors (check the famed 'CRT-Royale' shader available in RetroArch for instance, it's more advanced than MAME's integrated HLSL)
Although it is rather gimmicky and not necessary purely for gaming, it shines best with panels of resolutions higher than simply Full-HD.
Here's a couple of good 1440p/WQHD 25" monitors;
BenQ PD2500Q
Dell U2515H (or newer U2518D)
I'm letting you google the reviews to find out about lag, response, rotation, speakers etc
note of warning: using higher resolution draws more resources from your computer, and laptops aren't ideal for long sessions of intense use.
MAME and shooters should be fine, but if for instance you'd play late era Cave games that are very CPU intensive, and add a CRT shader on top, your computer might not be able to cope, and crawl, or it might play the games at full speed with some settings arrangement (not sure) but the overall heavy game + shader combination would remain very heavy. in short the same thing over a 1080p monitor would be a bit less intensive (but still)
- laptop
I was wondering if your mobile 1060 can produce G-Sync on an external compatible monitor (?) but I couldn't find the answer.
Adaptive Sync (nVidia's G-Sync and AMD's FreeSync) lets you run the emulated games at their original refresh rate and speed, no need to have vsync forced in the settings, it makes gaming smoother and tearing-free, more accurate and is even easier on gpu ressources.
You really need to make sure it works on external before considering a G-Sync compatible monitor though.
Also with few exceptions those are noticeably more expensive, and the more interesting models are at least 27"...(to develop only in the case you'd find out/ have any interest)
Personally I've been using a 32" full-hd

the excellent-for-the price ViewSonic VX3211-mh (good all-rounder), and I also have a 32" Samsung LS32F351 that's got an excellent VA panel for those who in priority like contrasted and vibrant colors and black/dark rendition, that kind is good for watching movies.
But those are overkill in size for most people, demand a big stand and enough room for rotating/moving.
Also they have a reflective (glossy) coating that some people don't like.