What are the benefits of purchasing a complete bike from a respectable brand? (Road cycling) I've been into cycling (almost) my whole life. I've been riding BMX for over 20 years and since 5-6 years I've been doing a lot of road cycling. I ride contests, crits, TT's,... 

I've been looking to get a new road bike for some time now. I outlined some requirements that this bike should have. With that out of the way I started looking around for my options, there are a wide variety of bikes that handle my needs. But coming from BMX I am used to building my bikes from the ground up. Changing parts as they broke, building completely new setups,... The only complete setup I ever got was the bike that got me started.

Apart from price, what are the benefits of purchasing a complete bike from a respectable brand? Canyon Aeroad CF SLX 9.0 DI2 for example, this bike meets the requirements and falls neatly in my budget. If I would start building my bike it would end up parts wise like the Aeroad. 

What not to take into consideration: I am technically able to build and maintain most bikes on my own. This should not be an issue.
Warranty - buying one bike from one supplier means the whole thing is under warranty.  New bike frames may have anything from one year to lifetime warranty, but often have a rider about "must be assembled by an authorised and qualified bike shop"

Integration - all the parts will physically fit into the frame quite well.  Stuff like internally routed cabling simply works better when the parts are all specified on the one build.

Compatibility - Its not your problem to make sure that a front mech and a chainring set match up.  A complete bike will work from new as it is supposed to with no fiddling and fettling.

Set price - a complete bike has a set cost.  A build has an unknown end cost because you may not find the parts you need at a fair price.  On the other side, the parts you need might be in your possession already so have zero net cost.

Timeliness - you want to ride your new bike, not spend time assembling and troubleshooting it.  

Suggestion : Since you can afford a high-level bike like a canyon, and time is valuable, just buy it and ride it and spend the time on maintenance.