I'd pick someone who can travel through time so my vacations are longer than 1 year. Though is tempting to have lots of money and live a free life with my kids.
Where is it said Superman is on our Earth, rather than you in DC earth?
I assumed it was DC/Marvel Earth, otherwise it's stupid because Tony wouldn't have his money/resources, so that would be a stupid pick, Bruce wouldn't have any money, Surfer wouldn't have his PC, Asgard doesn't exist on our Earth etc etc.
If however I got to spend 1 year with a comic book character I'd choose Vril Dox II.
With less than a week he could genetically enhance himself enough to fight evenly with Lobo. He built the genetically artificial body that became Pulsar stargave with class 100 strengrh invulnerability and the power of matter manip.
In similar fashion he worked out ways to deactivate the powers of Telepaths, shape shifters, and many other. He removed Lobo's regeneration from a drop of blood in a day. Created his enhanced charisma program that brainwashed all of Colu to love him and his son used to completely control a few galaxies.
So on a year I get my new best mate to make me a class 100 brick with TP, shape shifting, and matter manipulation powers. To create a subliminal program that makes every woman worship me like a sex God and every man give me what ever I ask and then I think of some more challenging requests
This isn't All Star Superman and we have no clue on how long that "different version" of Superman took to make that ingredient for her to get that power or how he did it. He did have a fortress of solitude in the book and he doesn't have that here. If you want power, Surfer is the best approach.
Superman always have the Fortress, also, this is a make believe scenario with make believe characters. Why can’t I choose All Star when the OP just said Superman?
You know what, I choose Golden Superman after he came back from the sun to power me.