Not sure I'd get a 2009-14 "Gen 1" being in California and not able to 'delete' the emissions equipment.
Overall, they're a simpler engine than the 2015, in the long term the very basic components of the long block may very well afford a longer life with fewer complications.
However, there were a lot of dumb things VW was still finding out the hard way with them. This was the biggest compromise engine since they do NOT have diesel exhaust fluid (DEF). And since the scandal, the "fix" they've had is seemingly even harder on the DPFs than they already were.
DPFs were already failing at a higher rate on Gen 1 engines than on any of the others and from what I'm hearing, the update just makes the failure rate worse and the parts are backordered for at least 2 months now. And, to top it off, these are the engines more known for the high pressure fuel pump failing. The Gen 2 and Gen 3 engines having DEF and solenoid injectors don't seem to need as much pressure from the pump as well as not needing as many injection events since they don't need trick programming for the injection system to help get NOx levels where they need to be since they can just increase the dosing rate of the DEF to compensate for any shortcomings there. It may also be that the piezo crystals are part of the problem in the gen 1 engines.
The 2015s are extra complex, but they won't suffer some of the common maladies that IBW already outlined. Less DPF failures, no intercooler icing (not that that will be a problem in Buellton's climate). The 2015s have numerous tricks to warm the engine up faster and decrease drag from various items to help eek out every last MPG. And in real world use, the 2015 engines absolutely get better MPGs. Aside from the occasional leaky DEF injector, I suspect the 2015s are going to be much more reliable from the emissions equipment standpoint.
But, you might have to replace the oil bathed toothed belt that drives the oil pump with every timing belt change. There's a couple flaps in the cooling system for added complexity. A computer controlled variable displacement oil pump and as IBW mentioned, a computer controlled sheath on the water pump (though aftermarket timing belt and water pump kits offer to delete that).
The other thing you won't have to worry about on the 2015 engine? The P2015 intake manifold flap position code. There are no flaps to worry about with that setup. And that's a pretty common failure on the gen 1 engines.
Though, if you want my opinion, the gen 2 engine, which only came in 2012-14 Passats, is a real nice happy medium. It maintains some of what makes the Gen 1 engines simpler, and increases the simplicity and addresses some of the common issues that plague the gen 1s.
The gen 2 engines use an air-water intercooler as well, but it's a separate piece from the intake manifold (gen 3s it's integrated as part of the intake). The shortblock is much more like the gen 1s, the head is different, but still much simpler than the gen 3s. They also use similar solenoid injectors to the gen 3s, thus requiring less pressure from the HPFP and they do seem to have a lower failure rate than the Gen 1s as well. Can't remember the last time I heard of a DPF failure on a gen 2 either. It's a very similar design to the gen 1, but it doesn't need such aggressive EGR duty cycles or trick fuel injection programming or micro-regens for a lean NOx trap like the gen 1 does. Seems to help with reliability of the emissions components and despite being in a significantly larger car, the gen 2 engines get better fuel economy than the gen 1s as well.
The gen 1s are a bit of a disappointment in terms of efficiency, especially with shorter commutes.
I'm still tempted to pick one up and see if religious use of good fuel additives and paying close attention to exhaust gas temperature spikes, indicating an active regen, and letting it finish and cool down before shutting off the engine yields a reasonably reliable gen 1. But I suspect ultimately will be let down by the downgrade in efficiency coming from an ALH.