Not ready to switch to Photos until it matures a bit more.
I’m currently using Aperture with the Beta El Capitan OS X.
Library opens fine.
I’m having two issues.
1) In Aperture, selecting import. The iPhone does not appear. I have set Aperture (within Aperture) to be the default import app, but it doesn’t appear.
2) I want Aperture to be the default import software but unable to work.
Thanks for your help.
Try to disconnect the iPhone and reconnect it (via USB) while your aperture is open. This works for me with Beta El Capitan.
I see this in Yosemite as well. Don't know when it started but I assume somewhat with the Aperture 3.6 update.
Doesn't annoy me though. I prefer to not auto-open any app when I connect a card reader or an iPhone because not always my intention is to import photos into Aperture.
Thus when I really want to import stuff, then I open Aperture first go to import and then connect the device, which works perfectly as Nic pointed out.