I flew EasyJet from Swissto UK in August. One thing to add about the hand baggage size limit. I was a little worried about my hand carry bag when I was at Zurich so I actually approached the counter and asked them if I need to check it in. The girl asked me if I have pre-paid online so I said no. She had a look at and said something "it does look a bit big..." but after consulting her colleague in German, they both just waved me through. However, on my way back, they are much stricter in Gatwick. Their staff insisted that I have to pay as the lugagge cannot be "comfortably fit in" the metal frame they have their and that this is a EasyJet policy that all hand baggage to comply. Of course, I am not giving in without a good debate. So after 15-min and a bruised finger (as I was demonstrating repeatedly how the piece can comfortably fit in the frame), I got through. I know it is not a lot of money, just don't feel like paying for the different standards.

I'm booking a Zurich-Gatwick-Zurich flight for late November. 2 adults, 1 infant. Easyjet and AerLingus come out at about the same price considering charges, baggage deals etc. Easyjet has the advantage of 2 flights per day, which means we get more time in London. AerLingus is still in my mind as a "proper" airline.

Has anyone had experience with either on this route and care to try and sway my booking preference?

Ive done this route with Aer Lingus, and it was a very good flight , and great service. Id definitely reccomend it over Sleazy jet...

I booked ages in advance an Aerlingus flight Geneva to Dublin this year, and just 2 weeks before departure they told me that the flight was cancelled.

It was the only flight of the day, so they just put me on the following day's flight instead. As it was important that I travelled on the original day, I ended up having to take a train to Zurich (at my expense) and fly from there, though of course the flight cost was identical.
I suppose cancellations may happen with any company, but at least if there are several flights per day, you have more options.
I have frequently flown with Easyjet and I have no complaints at all about them : I don't understand these "Sleazyjet" comments. Obviously you have to get informed about things like hand luggage rules beforehand, but if you read the information on the site when booking, there should be no trouble at the airport.