It depends on the type of leather I'm using it on.
My favorite is Blackrocks. It does add some waterproofing, but it hides blemishes and makes everything look better. I used it on my sunflower duffle to add a layer of protection against color transfer. I use it on pebbled leather to give it a sheen. I use it on every rehab.
For dry leather that isn't too pebbled, I use Leather CPR before Blackrocks.
For very dry leather, I use Leather Honey.
I have Lexol, which is comparable to Apple, but I don't use it much. Most of my new bags don't get conditioned. They don't seem to need it. It is hot and dry here too, not as much as Phoenix, but my bags live in an air-conditioned environment.
I also have Obenaufs. I haven't quite figured out what it exactly does, but in combination with everything else, it seems to add something. I used it on my Archival Rambler to reduce the shininess of the leather.
I also have Bick 4. I think that might be a good replacement for Apple. Another conditioner that gets rave reviews is Cadillac. I'll probably try it someday.
I wouldn't recommend Coach Leather conditioner, or any conditioner that has silicone.