Btwin FC 5

Did you go for it in the end? I see it's now showing as out of stock. I have 2 B'Twin bikes - a Triban 3a and an Alur 700. I use the Triban as my commuter and it does the trick (though it has started making a knocking sound when I pedal out of the saddle or when moving off from a stop) and the Alur I love. It too has Shimano 105 components and they are excellent.

TBH the biggest thing is that Decathlon offer a Lifetime warranty on the frame of all their bikes, Carbon inc. How many other manufactures can offer that?

I think BTwin/Decathlon stuff always offers good value for money - and it always performs well considering the price.

Then again the Cannondale CAAD8 is from one of the best alloy frame lineages in the history of road bikes.

If they both fit ok, then buy the one that you like the look of most, that will make you want to ride it.

Just bear in mind that the Cannondale would probably be easier to sell on secondhand should you get to that point for whatever reason in the future.

Shut your ears to the bike snobs and remember the manufacturers have sponsored pro tour riders. Look at other similar products carefully and the spec and decide if you are getting value for money, I would say with this bike you are, but that's just my opinion.