Looking for advice

I'm in the market for a new bike and have a budget of about €2000 - 2500. I ride all year round so it needs to be robust enough I found a Sensa Giulia G2 Di2 Matt Custom Road Bike - 2016, which I thought was good value. However, my local bike shop first said that those bike are an inherently rattley bike and that I would be annoyed within 20 minutes of riding. Then I had it explained to me that Di2 can be a complete pain in a the hole if things go wrong to get fixed.
However, I don't know enough about bikes to know any better.
I was then shown me a couple of orbea bikes with 105 and ultegra group sets.
Now, this is where I get really confused. The LBS was then recommending 105 over ultegra. The main reason being is there is no real difference between the two in terms of the way they feel and how they work. The only difference is weight (and price).
So I guess the advice I'm looking for is:
Are sensa bikes any better or worse than Orbea ir is my LBS trying to pull a fast one?
Is there any real reason to buy ultegra over 105?
Any help that can be offered would be greatly appreciated.
Thanks