No specific "gotta have" recommendations here, just some ideas based on personal experience...
I'm not trying to low-ball here, but LR runs quite capably, with no hiccups at all, with 36mp raw files on my 2012 MacBook Air with up-to-date OS. PS runs well, too, but has a few more slow-ups. Anything recent from Apple will run fine depending on how much you depend on PS, as it is much more of a hog than LR.
Consider also, if the laptop will be a secondary machine, then is PS even necessary to have on it?
Again, if your laptop is a secondary machine, then you could get away with using a Windows machine at half the price of a MacBook anything. I think you'll notice a difference in monitor quality and colour accuracy, though, especially if you are used to an iMac.
Lastly, if you end up purchasing a decent laptop, don't be surprised if you find six months down the road that you are editing more and more on the laptop. I certainly find it more comfortable sitting in my Poang editing on my 15” MacBook Pro then sitting at a desktop! The track pad is ideal, even if the screen real estate is smaller.