m0rd0r, I'm all for arranging a fat bank account to access at birth! Heck, yeah! So I'd have to choose time travel, too, although invisibility would be fun in certain situations (but not as much fun as going around fixing stuff!). And I'm sure there's a way to totally avoid the time travel police.
Another reason I'd choose time travel is I have a lonnnnggg list of people now dead I'd love to meet and chat with. Famous people, of course, just to see if the history books "got" them right. But mostly, certain ancestors who left behind many unanswered questions about where they went or what they did and why. Time travel would be the ONLY way to fill in gaps in the family history. Some of them, I suspect, would be thrilled to set the record straight.