If the airfare is just a hundred bucks more, or so, then from your list I'd pay to go with...
... but if it's much more, just take the cheaper flight and have more money to spend on good food and wine!
I've flown all the airlines you've spoken of - some are better than others, but it's really not a big enough to pay more than a hundred bucks, or so.
The best thing is to get a United flight and upgrade for economy plus, if you've got the money. WAY less money than first class and significantly more legroom.
Also, you're on your HONEYMOON!!! Drop that all over the place as you are getting your seats assigned (when you checkin your luggage). If you are really nice - and, ironically - don't push it too much (like you're trying to get them to upgrade you - if that makes sense) - there's a good chance you could get bumped up. Just ask the person behind the desk how their day is, tell them how excited you are, drop "husband" in there and act excited about finally being able to say that... it works a good amount of the time
Have a great trip! Italy is one of my favorite countries in the world!