Which is better for lighting a house's yard in California, a cobrahead or a bucket light? They're around the same price, but the bucket light could be easier to mount, and the cobra lower light trespass.

Is light trespass a big deal? There are many factors involved in making a good choice on what lighting to use. What are some of your goals and limitations? Heres some thoughts on what you have already provided:

-Cobraheads in my experience are a good bit heavier, especially with a glass lens. I think my AEL 125 weighs in around 50lbs. If trespass is a big deal you'll probably want to go with a flat glass variant, drop glass lenses still throw a lot of light around.
-Although more difficult to find, full cutoff buckets do exist.
-Wall/tall packs may also be another option. Since they mount flush to the wall there is usually less trespass into the building they are mounted to. Also since they have reflectors facing the building more of the light is reflected out away from the building and less light is wasted vs cobraheads or buckets.

-Wall/tall packs may also be another option. Since they mount flush to the wall there is usually less trespass into the building they are mounted to. Also since they have reflectors facing the building more of the light is reflected out away from the building and less light is wasted vs cobraheads or buckets.

The wall packs tend to overilluminate the area near the building, so the reflected light is as obtrusive as a cobrahead further away. And then the illuminated area is way smaller.

But it depend on the individual site needs: If the task is to illuminate narrow walkway around the building, a set of low power wall packs will do the job way better, on the other hand when the task is to illuminate a square parking lot, a single cobrahead on a reasonable mast will blow all others...