KEF vs Canton Bookshelf Speakers

i have the cantons and you won't need a sub unless your room is large.
you should hurry as there is only one pair left. although you can get them for the same price the canton is a much more expensive speaker (retail $4k).
CANTON Vento Reference 9.2 DC Bookshelf Speakers Piano Black Pair | Accessories4less

I have the 9.2 DC Cantons and they are great speakers.  Very neutral and a surprising amount of bass for their size and very attractive.  You might not "need" a sub, but they will definitely benefit from one.

I haven't heard the LS50, but have the Kef Reference 1 in my main system.  Not a fair comparison, but if the LS50 have some of the same characteristics, which I assume they would, you may get better soundstaging and imaging with the KEFs. 

My favorite monitors are Harbeth P3ESR.  You might not be able to push them as hard if listening loud is your thing, but to me they sound better than the Cantons and share many of the characteristics I like about the KEFs, lots of detail, great midrange, good imaging.

Back to the listening loud thing... I blew a woofer in one of the Cantons, so I wouldn't push them too hard either.

@big_greg

What are you pushing with? I've read that the KEF's can sound harsh with Class D amplification (which is what I have). I have a pair of Canton SL596's right now, and love them. Aesthetically they are just too big for the room.

For rock I’d go Cantons or theres a nice pair of Fritz Carbons at TMR that I’d recommend also.  If you don’t love the Carbons TMR would take them back I believe.