focus here seems to be on PAX comfort.
airlines are just as (likely far more) concerned with operating economics.
PAX comfort and CASM are inversely related.
PAX hate the single-aisle, 50 row 757-300 . . . NW/CO love them
PAX love the roomy, quick to board/de-plane A318 . . . airlines hate them

Re: E vs CRJ. There is little comparison between the two. E > CRJ. However, without knowing the acquisition costs/operating costs for AC, it's hard to make a final judgement.

BBD being MTL-based made a CRJ order from AC a lock. The relatively low CRJ component of AC's order make it plainly obvious the aircraft is not a winner.
If BBD's CSeries does not meet the targets put forth, they will be in big trouble. Only so many Q400s you can sell