A few thoughts.
BB interface is an important factor in the decision. Depending on how much you ride, it may make little difference or be a monumental factor.
ISIS - Becoming increasingly available. Some nice cranks are only available with this interface (Zipp, Pulsion). Due to the desire to create a non-proprietary super stiff spindle, the spec did not allow for bearings big enough to ensure good/great durability. The bearing diameter is 2mm, roughly the same size as a 14ga spoke. You will see people disagree on the durability of ISIS, but I also know of no pro racers (or riders who do very high volume) who haven't had problems. This is why companies like Phil Wood, or even Chris King, who was one of the three original manufacturers to endorse ISIS, have not come to market with an ISIS BB. Ceramic bearings have been suggested as a solution. IMO, ceramics are pretty much pointless in a BB, rpms are too low and they are more prone to contamination than anywhere else on the bike. The benefits to ceramic have little to no payoff for normal cycling. Ceramics are sometimes used for track and wheelchair hubs in the Olympics etc. where low drag, no lubrication, and maximum acceleration are key, and price is irrelevant.
Octalink - The Ultegra is a good, very durable, albeit heavy, BB. The lighter Dura-Ace can work well too, but does require more frequent maintenance to perform optimally. From a WW standpoint, the Ultegra is quite heavy, and the Dura-Ace is moderately light.
Square taper - An old standard. Nothing wonderful about it, except that it allows for the use of some great (super durable) BB's, such as the Phil Ti, or Am Classic Ti. For perspective, I had an old Phil Stainless Steel BB that had over 20,000 miles on it with one re-greasing and the bearings were still smooth.
Outboard bearings - Becoming more popular. From a design perspective, this is probably the way to go. It places the bearings as far out on the spindle as possible (helping stiffness), and allows for very large, durable bearings. The only problem is that most of the lightest cranks are not offered in this interface (yet). I believe that the THM-Carbones Clavicula is a notable exception. This may well be the ultimate WW crank/BB combo.
You might also consider the Storck Power Arms, which are very light and available in many of the BB types. That was going to be my choice, but a Cat Carbon crank became available, so being a good WW I snagged it and got a Phil Ti BB to go along. This combo will be very light, and should provide very high reliability and long service.
California does have its faults.