MacBook Air - nice and light. I even dropped a cup of coffee all over the keyboard when I just had it, 4 years ago. Still running without any issues besides battery life but that's probably my fault and easy to replace.
MacBook Air. Great design, really lightweight and should be good enough for coding. (editing photos etc will require a pro)
I use a 2009 MBP with 4G RAM and 240G SSD. Need to replace the battery. Still going strong.
If I was buying new, I would go for an 13" MBA with 8G RAM. The i7 upgrade is nice to have but not essential. As for storage I would settle for 256G SSD and use a USB3 external drive for backup and non-active storage.
For me: The 11" MBA screen is a bit small and battery life a bit limited. The MacBook keyboard bothers me and the 12" screen feels smallish too. My eyes are not that good, so the Retina screens don't make that much difference. YMMV.
Of course, if money was no object, then a 15" MBP with the lot would be my choice :-)