IF you've really been happy w/ the old speakers, then I'd probably suggest replacing the subwoofer first and then maybe adding an affordable pair of height speakers for Atmos if you want. And then beyond that, you might consider replacing the front 3 all at once if you can stretch the budget...
My current room dimensions are very similar to his 13x18 as well, and yeah, I ended up having to slim down my L/R speaker choice to allow the use of 120" screen for PJ. I'd guess most of those choices you listed might work in my situation, except the Monoprice speakers which are probably a bit...
Saw your other thread asking about this JBL 9.1 soundbar. Guess I'll link my reply here for everyone's benefit since people do sometimes check older posts for info, etc...
https://www.hometheaterforum.com/community/threads/jbl-9-1-soundbar-opinions-for-a-newbie.374701/post-5080253
_Man_
Sounds like dual Hsu ULS-15 Mk2 would be the way to go, if he can stretch the budget some. Might be wishing I went w/ one myself now instead of the VTF-3 Mk5 (as I'm much more space constrained these days)...
_Man_
FWIW, I only paid ~$1380 total (shipped) for my ELAC Uni-Fi UF52 floorstanders + UC52 center + Debut UB52 bookshelves (for surrounds) direct from ELAC. Bought them on one of their seemingly frequently recurring sales (and also got an extra 10% off offer... plus no sales tax direct from them)...
I could 2nd that, especially if prioritizing music playback -- it's basically what I'm now going with myself, except I have a slightly different Hsu sub (VTF-3 Mk5 HP that I've been keeping sealed) and might add a pair of ELAC OW4.2 (I already own) for rear surround (to get to 7.1). Well, I...
"Sound pretty amazing" tends to be very subjective... or some people wouldn't be spending 10-20x (or maybe even more) what your speakers cost to get what they find very satisfying... and sometimes that much just for the 2 front/main speakers alone.
Of course, not suggesting you should...
Since you want to go w/ PJ (on top of the sound difficulties), if it's doable, I'd probably strongly suggest closing off the area much more than it is now.
For instance, is there really a particularly compelling reason to keep the HT area completely open to what looks like a big in-eat kitchen...
@marter, have you actually tried some more optimized setup w/ your NHT speakers?
You mentioned the biggest issue for you has been trying to get intelligible dialog at low-to-modest volume levels. Has that always been an issue w/ this setup or was it originally fine, but gotten worse over time...
You could also try it w/ 1 next lower model Hsu (or maybe SVS) to save a bit and see if it comes close enough to satisfy, especially if you're new to this level of performance and is doing a livingroom HT, not dedicated HT room... unless you really plan to rattle the dishes quite a bit and shake...
Besides what John also replied, I suspect floorstanders might also be better around kids unless you really need to put the speakers on literal bookshelves (or whatever home entertainment center where the big TV also sits) or the like. I'd trust good floorstanders more than monitor/bookshelf...
Looks like a very solid choice in that range... though I imagine he may want to get a subwoofer sooner than later w/ something like that...
I might've gone w/ one of its predecessors myself if I didn't get my used Vandies way back when...
@Matt Fisher, you might also want to check out the ELAC...
Given your desires and constraints, I'd suggest considering going w/out a center channel and just focus on getting the best front/main speakers for now unless you have to keep the front/mains far apart, especially in some odd, poor performing placements to satisfy your wife. You can always add...
John mentioned Hsu as another option, especially if you want to go 15".
Hsu's VTF-3 Mk5 HP (w/ 15" driver) might be affordable enough for you? And you can adjust whether to run it (fully) ported (or partially/singly ported) or sealed to suit you. Right now, it costs same as the SVS SB-2000...