Help needed with bike purchase

Hi all and apologies for the dumb question I am going to ask!

I am 50+, overweight, not a fit cyclist and am dieting, training and aiming for Coast to Coast later this year along with other sportives.

I currently ride an old Giant Defy 1 which has served me well and completed the C2C last year but I want something new.

The advice needed is – which bike is best in the £2K-£3K range?

Do I stay with Giant (all my kit is branded!) and I like the look of the TCR Advanced 

I love the BMC Teammachine SLR01 (especially the Di2 !!)

I quite like the BMC Gran fondo range

I dont really like Specialised but the Roubaix has that suspension …… is it worthwhile?

I know I cant afford Cervelo, Pinarello etc and am not keen on Ridley, Fuji, Genesis, Planetx 

I would like Ultegra but know that 105 is probably all that I need!

I can see that buying 2016 stock or demo bikes will save me hundreds of pounds but is there any point buying old stock (from Evans for example…..) – do you get the same warranty as new?

As someone who will never rival Wiggins or Froome, what do I aim for ?

Any advice at all would be welcome.  Lots of people out there wil have tried several of these and others besides

Thanks for reading !