Buy men's jeans. Use the pockets. It's liberating, I promise, and a pair of good jeans costs about as much as a good bag (less if you shop at Goodwill/Salvation Army).
I think I was about six or seven when I declared that I would never, ever, ever, ever carry a purse. I think the catalyst was my mom asking me to hold hers while she did something...I was totally mortified. Early-onset femmephobia, I guess. But really, it's just so bloody annoying to be tied down to a bag.
A backpack or a messenger bag will work just fine when you actually have something substantial to carry. But if you're presenting as male/more masculine, your valuable-items-that-must-not-be-separated-from-your-person would still belong in your pockets even when carrying a bag, unless you're wearing skinny jeans (and even then, stuff like ID/credit cards still go in the pockets). Guys just don't have a bag that they treat as a purse.