First, Happy Birthday. Hope you enjoy a lovely trip.
When shopping/comparing business class seats (and really, most of it is all about the seat – food, drinks, and bling are less critical – first and foremost you want a comfortable seat), one important thing to be aware of is that you'll want to look specifically at the individual flight and aircraft type, not just compare airlines. Because (at least for some airlines), there isn't 100% consistency across every business class seat on every flight, and you may find significant differences between what are all called "business class" or something like it. Some airlines have a mix of aircraft types, and even within a single aircraft type on a single airline, the seats may vary quite a lot depending on the particular aircraft you get. To further complicate things, on some routes, you won't know until just a couple days before the flight which business class cabin you're going to get (I'm looking at you, American Airlines...). And of course, last minute aircraft swaps for mechanical or other reasons do happen, and there can be surprise changes at the last minute. So all that complicates the comparison.
Generally speaking, of the list of airlines you list above, I think Swiss might get the edge (good seat, they have a reputation for good food and service); Air Canada, British Airways, and (sometimes/usually) American have a pretty solid business class product. Iberia is also pretty good, but may lack some of the "soft product" (service) touches. Icelandair would not be one of the more highly-rated options. Finnair has a new, somewhat controversial business class seat that gets very mixed reviews (it does not recline at all, rather you kind of "slouch" down in the seat to sleep, but that's offset by having a larger, more open, and somewhat unconventional space, and large pillows). Some folks love the new Finnair business class seat, others hate it.
One other variable you should certainly include in your considerations is the flight routings, layovers and schedule. That's going to have as much of an impact on how much you enjoy the flight as whose logo is painted on the plane. Nonstops are always nice, but they're sometimes hard to snag, especially from the US west coast. San Diego being a mid-sized market (I think) and not a giant airline hub (welcome to the club, I feel your pain), you will have fewer nonstop options to choose from. If you don't mind a connection in LAX or SFO, that'll open up more choices. But I would recommend you try to avoid a connection elsewhere in North America; I always try to maximize the time in my long-haul, trans-Atlantic flight (gives you enough time for a meal, maybe a movie, and still have enough time to get some solid sleep....if you break the flight up by connecting in central/eastern North America, you end up with two flights that are not long enough to get good sleep, and for me, business class is mostly about sleeping and arriving feeling fresh and rested...so if you have to connect, I'd try to do it at another west coast airport, LAX, SFO, PDX, SEA or YVR).
Hope that helps. Enjoy your trip.
