I know that hand welting is more durable than goodyear machine welting, but what are the aesthetic differences between the two?
AS Bengal said, there's no aesthetic difference at all because u can't see the the welt stitching.
Whether a shoe is hand-welted or not tells u nothing about how it looks, and of course there's lots of great - Grenson, Trickers, Edward Green, Cheaney, Alden to name a few - machine-welted shoes.
Just depends on what your priorities are.
All other things being equal - almost never in shoes! - I buy hand-welted.
re: Man of Lint
my 2 cents take or leave- Apart from one or two anecdotes on SF I've not heard of or seen any evidence that hand-welting improves the function of the shoe.
To me it's not a matter of function or appearance. I don't worry that EGs are going to fail because they are Goodyear Welted.
I just like knowing some of my shoes are mostly made without machinery, altho I draw the line at a hand-stitched upper. I've not seen one that doesn't look like something from an archaeological dig!