How many bikes have you tried?
Have you tried both sizes in practice? Have you tried different bikes? Are you really sure about the bike’s geometry?
Frame geometry is much more important than groupset or e. g. whether the frame is made of carbon or aluminum. When I first got a road bike, I opted for an endurance road bike as well. On paper, it made sense as the position was closer to that of an XC mountain bike. I never got along with it, the steering was slugging and I actually feel more comfortable on my more aggressive aero road bike. Even among endurance road bikes there is a lot of variation. BMC’s Roadmachine is more aggressive, so it carves corners better than my Cube Attain GTC SL that I owned previously. (Cube, just like Canyon, is usually a lot of bang for your buck/Euro. On the flip side, their bike designs are typically middle-of-the-road, quite conservative. Think VW Golf — a great car, but not an exciting car.)
I test rode a lot of bikes, including Cannondales and BMCs, and settled on a 3T Strada in the end.