I'd seriously just buy what I wanted if I were you. I know that whole Freesync thing looks good on paper, but buy today what you can enjoy for years and ignore the gambling aspect of what comes next in tech, because it usually isn't quite enough. Buy what works today and carry on.
I liked the G-Sync 60Hz featured on my MSI GT72 Dominator when I got it (17", 1080p, IPS, GTX 970m), so I figure that Freesync @60Hz for a 43" shouldn't be too shabby, maybe even for a slight trade-off in speed. We'll see in a month or two.
The current G-Sync monitor lineup doesn't really appeal to me (as the trade away in terms of screen real estate is way too much for me to deal with; last year, I went into the local MicroCenter and found the 34" 3440x1440p to be considerably smaller than my 42" 4K, enough so that the G-Sync appeal didn't make up for it).