Which MacBook Should I Get?

Looking to buy either MacBook Air or mac book Pro
I can have a 2017 Pro for app same price as 2018 Air- but Air would have 256GB harddrive.
I have an late 2012 Imac+ Ipads+ iPhones- main use – excel sheets, word docs, internet & photo’s ( app 15k photos- using Apple photo app)
QUESTION’s- Which do you think I should go for?
With with can I upgrade RAM myself?
Thank you
—–
Graham