Like I say, I don't really follow the muddled line-up of Macbooks...
I see there's a new Macbook Air that seems mostly comparable with the bottom Macbook Pros. Eh? I'm geniunely not sure what they're thinking.
The usual advice applies, unless you have special requirements (video rendering, games etc.), any modern laptop is unlikely to break a sweat, so it's really a case of what you like and your budget. If anyone can make sense of modern processors (oh for the simple days of I-want-the-one-with-the-most-gigahertz) they're smarter than me. I wouldn't pay a premium for a modest bump in processor. 8 GB RAM is generally fine unless you really feel the urge to mangle giant spreadsheets and databases.
Things that are important to me – decent keyboard (a given on all models), force-touch trackpad (the bottom Macbook Air doesn't have one), and retina screen (my single favourite thing, and you can't go back to lower res, it's horrid). I think they all have USB-C. Some of the upstream models of the Pro have the touch bar thing – it's actually useful, but far from life-changing.
Other thing is battery life if that's important.
As mentioned there are decent deals sometimes with refurbs, and you can get older models from various stockists.