Firstly I/we say that to everyone.Right, the moment several of you (I'm looking particularly at you, @Stat Brother) predicted has come. I need a new bike.
Secondly and most importantly, there's no point buying a bike if you're not going to get a cap.
What you basically have is a choice between a Ford, Vauxhall, Honda & Toyota. (I'm not being derogatory)
4 very good bikes, keenly priced and won't let you down.
They are all the same, but different, you don't want to get too hung up on the intricacies of the spec.
Saying that though the wheels are important and as you're in the flat lands all you should need is a regular double chainset.
As said you need to try them all, if you're really lucky one will stand out, I have my doubts though, for the reasons above. (they are good bikes).
The bike you WILL ride the most is the one that makes you smile.
Bold is right in that you don't want to be sold short, but your heart needs to be heard too.
(You try and take his Bianchi off of him)
If you only make the decision with your head, weighing up this front brake v that rear sprocket, you may well miss the bike you'll do an extra 5,000 miles on, just cos you loves it.
I appreciate that all sounds a little twatty and 'far out man'.
But if you take to cycling and find yourself effortlessly sailing along a flat road with a tail wind and the sun on your back, in harmony on your bike that you love, (what's not too love) you won't give a flying fudge if it's Tiagra 105 or Huret 5 speed.
Helmet, pedals, shoes, clothing all do come at a price, so don't over stretch on the bike (in every sense of the word)