This discussion is as dumb as the Ford vs Chevy arguements.

There are a few points to be aware:

1/ The original CRJ entered into service in 1994 and there was nothing else in the 50 seat field for speed and range. The CRJ opened a lot of new routes for AC when 'Open Skies' took effect that year and did it a lot cheaper than the only other jet they had the DC9.

2/ The CRA was an add-on type for AC in 2005 that allowed them to put 75 seats into the same markets as the 50 seater without acquiring a new aircraft type rating. Since the CRJ's had been transfered to Jazz the CRA was capped at 75 seats (instead of the design 90 seats) and sent to Jazz for commonality.

3/ The ERJ-190 was a purchase by Air Canada to get a 95 to 100 seat airplane to replace the DC9 but with a range up to 5 hours. A DC9 size with 2 hours greater range.

4/ The ERJ-175 came into play in 2005 because another carrier had already ordered them but did not want to take delivery. It was a quick way to get more airplanes into the air. It went to mainline because the big brother had to be flown by mainline due to pilot contract clauses.