The classic please for the love of god help me decide post!

Yep: buy one of them. You started off with a tidy list so you've done your research, and In 3 years' time you'll have 5 bikes and won't remember this fuss.

I recommend giving your list to any female friends, relatives and partners, and asking them to make a decision together, in order to speed things up a bit.

Aluminum would be better at that price point, it may even weigh the same or possibly even less then CF at the same price point.  And since AL frames are cheaper to make it means you'll get better components which you might appreciate it as the miles roll by and the better components have less issues.

Specialize makes a rocket aluminum bike called the Allez Sprint Comp with all 105 for $1,800; or you can save a lot of money and go with the number one rated bike for the money under $2,000 the Allez Elite again with 105 for just $1,200.  Personally for the kind of riding you say you do, I think the Alles Elite will more than satisfy you.

Check out pauls and ash they usually have a selection of giants on offer but they will be last year's models. If they have your size...

I have a 2016 Propel, carbon with Ultegra, coming up to 20,000 km now.  I love it!  I do about 100 miles a week, usually a couple of hours to and from work and then a longer ride at weekends.  I've never found the brakes an issue, in fact I would say they are the best rim brakes I have ever come across.  Then again, the brakes aren't actually Ultegra because they sit behind the forks at the front.  Is the one you quote the one at Cyclesense?  Looks like the same brakes to me but rebranded Giant Speed Control (!)

I did an Everesting on it a couple of years ago, 330 km and 27 hours, so it isn't too racy/uncomfortable.  You possibly want to try one to be sure though.  

I have ridden an older TCR which I found MORE uncomfortable than my Propel, but that was mainly down to the saddle which would give me grief after about 30 minutes.

The only issue with the Propel is it isn't very winter friendly.  If you are planning on riding through the autumn and winter I would think about a second bike to use when the weather is bad.  The Propel's brakes are susceptible to mud and cack getting into them from the roads and they are hard to keep clean/working well. I don't have a choice, but will do more mtb miles when the weather is bad.

TCR is awesome and just surges forward.  Incredibly it can also soak up the bumps.

Propel is fast as hell, but not brilliant on crappy British Roads.

Boardman doesnt really have that surge feeling.

I would go TCR.

 I wouldn't wory about Carbon vs Aluminium; I have both and my favourite bike is aluminium, as is the bike I race on. I'd just pick which bike you like the look of the most.

Both the Giants are good options! I'd recommend going for a carbon frame with 105.

Both the Gaints don't have particularly great wheels (as with most Giants) - there's a lot of upgrade potential there (though it's no reason to discount them!). A couple of my mates have the Giant Propel, they say the brakes are underwhelming and have upgraded - there's plenty of people online complaining about the braking too (the Giant Trinity also suffers from similar appaling aero brake performance)!

The Boardman looks pretty good, particularly the frame. The Tektro brakes will be underwhelming, if they are anything like the Tektro's I had!

I'd go for either the Propel or TCR - the TCR also got bike of the year from Cycling Plus! The propel is the better option for aero

You won't go wrong with any of these bikes, but the TCR at £1100 does seem like a sure bet.

I'm bias though as I'm on my second TCR one now. I believe they come with tubeless sealant and valves as well as an added bonus. 

TCR for me. £1,100 is a bargain for a fantastic frame which you can upgrade over time as bits wear out and you'll end up with a great bike which is as fast as anything else out there.