TN Pros and Cons
2) higher refresh rate (1ms typically so you have less stutter/lag if i rmb correctly)
1) not as vibrant as IPS in terms of color reproduction and accuracy
2) Bad viewing angle in contrast to IPS
IPS Pros and Cons
1) Better viewing angle [178 degrees overall]
2) better color reproduction and accuracy [sRGB/color gamut]
1) expensive af but again, quality and difficulty of producing these panels (especially if they were to have fast frame rates!!!)
2) lower refresh rate in contrast to TN (asus has a 4ms one in their exp lineup which i deem quite excellent given the challenges associated.)
if me personally i'll spring for IPS displays, the refresh rate difference means nothing to me imo... but colors do enhance the experience so YMMV.
also being a photographer/videographer whilst a gamer on the side, ips is a must for me and the desire for faster refresh rates isn't a necessity to me... maybe if your intention is to play more fps games and are less concerned with quality of color/viewing angles then a TN model shud suffice. whilst saving you cost...
From what I seen, asus and viewsonic are almost the same, with the differences being the design. then again the difference in Australia was 200aud for viewsonic and asus pg279q ... essentially you are going to decide between these two monitors based on the design you like. i would base my decision between these two purely because i need an all-in-one monitor and these two fit the bill [and also i value superb color reproduction which TN fails to deliver], i for one think these two are priced fairly given the challenges associated with cramming all 4 in one [fast refresh rates!, IPSpanel , 144/165Hz frame rates and 1440p resolution into an all-in-one package].
if you dont need ips or that superb color accuracy then spring for dell and save yourself abit of $$ you'll still get 144Hz goody at a 1440p resolution