@ ChrisR What in your opinion makes Aperture much better?
Well, it was mostly a joke... I'm an Aperture user for historical reasons (easier to move to from iPhoto). Aperture is, or was, described by many as being more consistent and better organised than LR. However, Apple announced a year or so ago that they were stopping development in favour of a very crippled mass market Photos app. So, I can continue using Aperture 3 until I need to move to an OS version that no longer supports it.
Both LR and Aperture (A3) are digital asset management systems with added raw development and basic editing (but all the basic edits you'd use in a real darkroom, eg contrast adjustments, dodge and burn, spotting and cloning, many others...). Another thing both LR and A3 have in common compared with PS is
non-destructive editing. The image in my files system never changes, unless I specifically ask it to create a new version. Instead, A3 stores the edit instructions along with the master. What I see on my screen (while the image is in Aperture) is the master modified by those edit instructions, which I can change or remove at any time. They only get fixed (in my workflow) when I export a version to upload for TP or elsewhere.
By comparison, PS is inherently destructive editing, which is why you have to do all your editing in layers that are copies of the original images (IIUC). Those layers are of course a strength as well as a weakness, allowing you to do things you couldn't in A3 (or, presumably LR). However, I have very rarely found a situation where I really needed to edit an image with PSE rather than Aperture (and it is very simple to do, simple menu item to call PSE, save on exit and the adjusted image appears back in A3).
One side effect of using PSE that I've noted is that image size balloons hugely. Aperture images stay small.
You may know all this, but seems worth saying...
EDIT: I have to decide some time if I'm going to change to LR, or an alternative like Capture One Pro, or maybe the DxO one, which doesn't have a DAM inbuilt...