I think it's a toss-up.
AllEars does a pretty good job of keeping things current. And at least, they post the date of the latest update.
Disneyworld.com...well, you'd think they'd have the latest update, but given Disney IT's reputation, I don't know that I'd be confident that they are that on the ball. It's possible, but there's really no way to be sure unless they start posting the date the menu was updated right there.
eTicket...again, probably fairly up to date, but unless there's a dedicated person who's going to each of these restaurants on a regular basis and checking for changes, it's possible something could be "that new" that they haven't caught up to it yet.
Bottom line: There's probably no way to know about every single restaurant.
For me, I always check AllEars first because they date their entries. If it's something I consider out of date, I'll check disneyworld.com. When the eTicket people realize that Android phone users are a market to pitch to, I'll have an opinion on it.