I should start with speakers. This I know. I’d like to establish a new system.

I still own/have owned 1/2 of the speakers that somebody listed above.

If you post you want opinions on a speaker, 100 people will reply with a 100 different recommendations. IMO, start going to audio shows like the Tampa Show this weekend and you will see maybe 100 different speakers.

There are many speakers that are better than the kef blades for quite a bit less money. If you want some great sounding speakers for your room, used, you can pick up a pair of Revel Salon 2’s for $10k and would never need another speaker, then you will need a very good amp to power them. Look at the Usher BE10’s used for $7k, Usher BE20’s for $10k used, or the Totem Winds for $5k-$8k.

If you want something very close to the Kef Blades for 1/5 the cost, look at the Kef LS60’s that are active meaning they have the amps/dacs built in to the speakers. I’ve auditioned both speakers in the same largish room and I would buy the LS60’s. All you need is an Ethernet cable (or WiFi) and power to each speaker and you are done. Because you have a large room, I would also add 2 of the Kef subs which are easy to add to the LS60’s via the Kef app on your iPhone. 

I used to own the Revel Salon1 for 5 years and have heard the Salon2 a few times. For my ears the Salons are not as fun as the Blades. The thing with the Blades is that the soundstage on that thing is incredible. The aluminum Blade drivers are not my favorite but that soundstage, especially on a long wall placement is the best I have heard. I always have fun listening to the Blades.

In terms of cone drivers, I have not heard anything better than the Zylon drivers in the Yamaha NS5000. The Zylon is similar to Beryllium (BE) in the tweeter of the Salon2. However, while companies like Paradigm can make a BE tweeter and midrange in the Persona lineup, Yamaha is the only company to make tweeter, mid, and woofer from the SAME material. What that means is an incredibly coherent sound, especially when the cone material maybe the best around. Yamaha actually had the first BE tweeter and mid in the 1970’s in the NS1000.

I love the soundstage on the Blades and love the sound of the NS5000. My ideal speaker is a Blade with Zylon drivers. Even the Paradigm Persona 9H with Zylon (instead of BE and the woofer material) would be something special.

Saying all of this, the Blades are great, the NS5000 is great, and the Persona can be made great with some work. I take the NS5000 from this cohort.

@toontrader, when I read @tomcarr 's comment 

Acoustic treatment.

The room will dictate at least 50% of what your system will sound like.

followed by @hilde45 's

If I was in the position of the OP, I do the following:
1. Try to size up the assets and challenges of the acoustics of the room. 
I'd lay hands on whatever gear I can find to listen with.
I'd listen, position, and once some reasonable positioning is established, I'd measure for frequency response.
2. With the information gained above, I'd try to treat the rooms major flaws, focusing first on 20hz to 300 hz, since those frequencies have to be mastered before dealing with the rest of the range. I'd work a bit, next, on 300hz-20khz.
3. Having brought the room to a baseline of decent response, I'd do a bit of research on speakers and amps that will match my tastes and my room.
4. Next, I'd start borrowing speakers or buying, used. I'd get a decent solid state amp (used, hopefully a keeper) that can drive a bunch of speakers.
That would be the "launch sequence" to getting the basis of a good system going, in my opinion.
Sum:
Get the room ready.
-Try speakers and amp.
-Get final speakers.
-Get final amp.
-Figure out how to optimize the rest (preamp, DAC, cables, power, additional   treatments, subs)

I suspect that many of us got the first part of 'Sum' bass ackwards either long ago or too recently to be entirely comfy with, so....

New home?  Lucky....built to a plan of theirs' or yours'?  Make a sketch or copy that area of the plan with door/windows/ac plugs with the ceiling detail(s).  Dimension all.  Have it on phone or laptop when you prowl the B&M's.  Consider the what, where, and why.
Buy used for test purposes; if you absolutely must have a That, work on timing for a demo in situ. Or consider a gently used part of the (never, really) Final Outcome.

Have a great time. ;)  👍😎 J

@hilde45 OMG, I shrank your post. 🙄

@hilde45 You have given some great advice

@toontrader let’s circle back on your room dimensions. They could be a real challenge or you could do something really specia. The long wall may very well play into an outstanding fit for large Magnepans like the 3.7i and a sub(s), and something quite different on the narrow end, maybe British and more ’intimate’. KEF F, B&W amd Monitor Audio all offer excellent choices for that application. It really is a unique opportunity.

On the other hand, it think the room is just too long to be well served by a single pair of traditional cone speakers. Horns biggest benefit  is controlled directives, which could make a very small listening window if used on the long wall. Cones might have broader coverage, but thats a lot of room volume for them to fill with the amps being mentioned.