Definitely go for the Canon T3, you'll get much better image quality, and have way more control and room to grow. You'll often encounter low light situations taking wedding photos where being able to shoot without a flash will get much more natural looking photos, and with the T3 you'll be able to bump up the ISO higher and still get good quality photos.
Check out our sister site LensHero, I'd recommend you get a 50mm prime lens for the T3, its great for portraits and details, and its wide aperture will let you get natural light shots you couldn't get otherwise, and blur the background!
