What type of build are you planning? The Swift is a top end gaming monitor. Not only does it have Gsync, but it's also 2560x1440. If you go that route your system needs to be able to keep up at that resolution.
I have the following monitors:
Samsung 950D (TN, 4k)
Dell U3011(IPS, 2560x1600),
Asus RoG Swift (TN, 2560x1440)
Asus 23'' (TN, 1080p,120hz)
I would put the Swift and U3011 at a tie, Asus 120hz, and the Samsung last. If I was forced to choose I'd give the nudge to the Swift. IPS definitely makes a difference, however I feel that the combination of the 1440p resolution and 144hz of the Swift evens out the battle. The Swift is very usable for day to day computing tasks. You definitely notice the refresh rate, and in gaming there is zero comparison between the Swift and these other monitors.
Getting the Swift means that the rest of your machine needs to configured in a way to take advantage of its features. You don't want to spend $800 on a monitor and not be able to truly enjoy it. With that said it is a lot of money and if you don't want to go this route, I would look into some of the 120hz/144hz monitors instead of the Viewsonic that you currently have. Even without Gsync I think the refresh rate would make an immediate difference to you in all games, and in day to day tasks.