Which magnepan

Ive had both 1.7 & now 3.7 in a similar sized room.  They both work : but 1.7's will give you somewhat more placement flexibility.  I would not go smaller than 1.7 in that room.

Re : other non planar options - would definitely take the KEF's on the list - unless you just want to listen to vocals.  

went to the closest Magnepan dealer today and listened to the .7 and the 1.7i's.            

the .7's were good, but it seemed like something was missing.....like not enough midrange and some detail was missing.     think with these, a sub would be needed as there wasnt enough low end.    

1.7i .     much more detail can be heard and low end was a lot better compared to the .7's .     a sub could always be added later if needed.   

I ended up getting the 1.7i's and will be ordered Monday and should be here in a week or so.

Congratulations.  I hope you enjoy them as much as I do mine.

I have the 1.7i as well.... VTL 2.5 preamp, Bryston 4b, Schiit DAC, UltraRendu fed by W4S power supply. King Cobra RCA & Kimber 12TC.

The other day I was looking at an extra NHT sub setting in storage... idea!
I ran speaker level through the sub (it's in center) x-over at 50hz.
My Maggie's are approx. 4' from back wall, 7" from sides, toed in 2" with tweeters out. 12' x 21' room... listening at about 2/3 back... ATS room treatment at rear and first reflection.
WOW!?!
I can't believe what I'm hearing... dead center image... speakers completely disappear... images depth far beyond all walls (front, back,sides) this sounds like I'm sitting in the perfect spot at a concert.
WTH? This was for fun.... but now I want to experiment with higher quality subs.... or maybe not???    ;)

The 3.7i should fit in your room.  I have a 24'x15'10' room.  The length actually continues another 10'-15' beyond a kitchen counter.  I have the speakers 10' and 8' off the front wall (irregularly shaped), and it sounds glorious.