I haven't read Daredevil, Aquaman is pretty good but I can name a few comics other than these two that are good ; Batman, Hawkeye, The Flash, Batman and Robin, Batwoman, Uncanny X-Men are pretty great.
Well he's already reading Hawkeye.
Based on your current comic choices, I voted for Daredevil. Hawkeye and Deadpool are pretty casual-oriented, and Waid's run, while not necessarily casual or new-reader focused, has a similar tone. It's a lot like Thor, actually.
Aquaman, on the other hand, isn't that great right now. I liked the first arc, but I got bored when it started requiring you to buy Justice League.
Looks like the vote was split on which was the better ongoing series to start. I guess the only thing to do, as many of you recommended, is to read both. Which is probably what I would have done eventually anyway. Thanks everyone for your votes and your opinions. Much appreciated!