There are several 'no names' that aren't so bad, but most are to be avoided. Why they are bad in workmanship that usually translates to handling noise - noise that gets picked up from the camera by usage, even focusing the lens or zooming, and in just longevity of the mic.
I use an AudioTechnia brand that is more than twice the cost of the Rode mode, but likely doesn't deliver twice the quality of sound, so be aware that cost is not the total deciding factor. AT's are built a tiny bit better, but at that level, a tiny bit in quality costs quite a bit more.
For weddings, handling noise will be important to you as directional quality to your sound. You'll want a high-quality shotgun mic with terrific handing quality in a really good shock mount. That way you can leave your camera running while adjusting it and not getting any of your sounds touching the camera. You also want to minimize the side comments next to you.
The Rode shock mount is great. I like the short AudioTechnia shotgun, but I'm guessing that the Rode shotgun is pretty good, too.