I would go for Chevron. From what I've heard from some ex-SHELL staff who resigned to one particular company (name withheld...lol) , it's a bit hard to rise up the ladder due to politics & an 'abundance' of 'qualified' individuals. Also, to me it seems Shell's structure is becoming more 'Nigerian'. I think Chevron would give you more of the International Standard.
Congrats bro, yours is a unique & inspiring story.