Just a few recommendations to begin;
- you shouldn't - ever - pick a monitor with a TN panel, because those are bad and banned for portrait/tate (extremely narrow viewing angles making about half of the screen go dark).
- IPS and VA panels are the only 'tate-able' lcd panel types, check here if you want to learn about the different panel technologies:
http://pcmonitors.info/articles/lcd-pan ... -explored/.
- what you read as '2ms lag' isn't lag, it's a figure for advertising grey-to-grey pixel response time (real input lag is never advertised, you can only learn about it when reading reviews from specialized websites).
Compared to TN panels, IPS and VA panels show slower response times, yes, okay... but still fast-enough for a huge majority of game genres.
Response time isn't the 'absolute everything' as long as you're not madly into games like FPS.
- PWM-free (flicker-free) monitors are now widely available and highly recommended especially for people who are sensitive to that kind of stuff.
- Standard Full HD monitors (1920x1080 at 60Hz) are enough for console gaming and overall pc multimedia use.
Higher resolution monitors like 1440p are generally meant for more involved use (not just casual gaming/internet/movies) but are still okay, though usually more expensive and with a little more input lag.
Higher frequency monitors (120Hz, 144Hz) are generally TN panels almost exclusively meant for pc FPS gaming, consoles or emulators don't benefit from those.
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prad.de,
tftcentral.co.uk,
pcmonitors.info have plenty of serious reviews, strongly recommended websites.
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Examples of some of the best tate-able 24" as of Aug 2014;
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Iiyama Prolite X2483HSU-B1 (VA panel) -> no rotating stand but VESA compatible so you can buy a cheap stand separately.
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Dell U2414H and
P2414H (IPS panel) -> main difference btw the two models is connectivity. rotating stand included.
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BenQ BL2411PT (IPS panel) -> if you still want to go a little bit higher resolution without wasting too many pixels. it's the best 16:10 around.
And some 27;
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Iiyama ProLite XB2783HSU-B1 (VA panel) -> big brother of the X2483HSU, but the rotating stand is included this time. Excellent.
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Eizo FlexScan EV2736W (IPS panel) -> excellent 1440p monitor but damn expensive.
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AOC q2770Pqu (IPS panel) -> more affordable 1440p.
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Samsung S27D390H and
S27D590P (IPS panel) -> both are excellent 1080p IPS(PLS), quite fast, but completely lack rotation or VESA mounting. just wanted to mention those as they're still better performers compared to many 1440p, and quite cheaper.
Personally I'd pick one of the Iiyamas (24" or 27"), but please take your time to read about all those.
PS: Astraea and Fudoh beat me to it. ^^