MacAceUpdater is the kissing cousin to WoW Ace Updater, and in many ways is more the redheaded-stepchild. My biggest gripe is that I can't filter the AddOns by the ones I only have installed. Sure, I can select and update all the outdated AddOns with one click, but it'd be nice to see the ones I have installed and require updating without scrolling through a massive list that's only partially relevant. The listing is in a really funky order, too. It sorts by descending order of the updated version number of the AddOn, so it's possible to have all of the Big Wigs components strewn through the list. Clicking on the headers to try and re-sort based on name didn't accomplish anything. I also noticed while quickly scanning through a printout my of my installed AddOns there were a significant amount of omissions. For instance, TomTom and KhunterTimers weren't on the list. It makes sense because it's focusing solely on Ace-based AddOns, but unless you use only Ace AddOns, it's not going to work as a one-stop solution.
That's why I prefer WoWMatrix. When I launch the application, the default view shows all my installed AddOns; the ones that have updates are in bold. The list is sorted by name, making it very easy to see what AddOns I have installed, and quickly update the one I need. Often, I'm just updating one or two key AddOns before a raid (Omen being one that'll I just grab when there's a new version to cut down on sync issues). However, as in MacAceUpdater clicking the columns to try and re-sort didn't work. However, sorting by name is the only one I'm likely to use so it's not a problem. Since it's not only searching for Ace AddOns the list is much more inclusive. What's also nice is I can select all of my AddOns in and export them with. or without, descriptions to a text file or a Wordpress widget. I'm not entirely sure why people feel the need to have a widget on their blog listing all their AddOns, but, there's a lot people do with their blogs that make me scratch my head. However, I can see the value in the text dump so you can reinstall if your system dies -- assuming of course at least that file is backed up. Actually, it'd be fantastic if it dumped the file in such a way so you could load the file, and then have WoWMatrix reinstall all the AddOns.
One area both programs fall down on is patch notes. Neither of them tell me what's updated in the new version. I usually only patch if it's solving a problem I have, or introduces new functionality - again, "syncing" AddOns like Recount and SWStats always get updated.. For me, there's little reason to update "just because" since, well, every now and then the update breaks something that did work. It'd be nice if I could press Command-I and get the patch notes for each version. I'm especially leery of updating my big AddOns like Pitbull. Having my whole UI go kablooky (yes, that's a technical term) right before a raid would not make my night. Also, it'd be nice to know if the new version fixes problems caused by the last Blizzard patch, and if they are are even compatible with the current patch. Ok, I guess what I'm looking for is a blink tag (kidding) that means, "really, silly, you need to update this patch right now. Yes, before you log in." For the more adventurous it'd be handy if you ran the program, it auto-updated everything, and then kicked off the WoW Launcher. However, having something run and then load anything related to my login credentials scares the bejeezus out of me. Which conveniently brings me to security.
While there have been no reports of any security issues with either of these programs, I'd be remiss if I didn't mention a certain amount of "buyer beware." You are trusting a third party to update your AddOns. However, due to how both the AddOns work -- they aren't executed like an application file, but rather loaded by WoW --, as well the generally more-secure-than-Windows operating system OS X is - your chances of having a security issue are very slim. It is something too keep in mind, though.
While there are other AddOn Managers out there, WoWMatrix was the one I had the best luck with. If, like me, you run too many AddOns and are horrid at updating them, check it out. If you know of one better, leave a comment and I'll check it out. You can't have enough AddOn Managers, can you?