Wire is the smarter pick for longevity in sunny, dry regions.
Last month, I was putting up a fence on a steep hill. Most crews I know swear by using concrete for every post. But I tried a gravel and stone base instead. It handled the water runoff way better and hasn't shifted at all. So, I'm not going back to concrete on slopes, no matter what others say.
I used to swear by steel posts for every fence job, thinking they were unbeatable. After a project near the ocean where rust ate through them in a year, I had to rethink. I tried aluminum on a buddy's advice, and it held up without a speck of corrosion. Handling it is way easier, cutting my setup time by a third. Now I push aluminum for most homes because clients avoid constant touch-ups. The extra cost upfront pays off with less hassle down the road. I only keep steel for heavy industrial stuff now.