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 :-)