To give a counter-opinion in favour of Samsung, I am using a Galaxy Tab S 8.4, and I find useful some of their custom ROM features like Power Saving mode (which restricts background data and runs in black-and-white mode), the split screen mode (very useful when say comparing excerpts from 2 book, or say running a calculator and another app.

Yes, they do try to bundle a few additional third-party apps like Flipboard, Evernote, and Dropbox. I wouldn't call these bloatware as these are high quality apps that most people would actually like and find useful, but I am mildly annoyed at the imposition. They also have a few of their own google-like apps and services like S Voice, S Planner and S Finder. These are basically attempts by Samsung to pull a Google (which frankly, they don't have the chops for). On the whole, i would say these additions are only mildly annoying since performance hasn't been much impacted, probably because of the hardware(but this may change with time and updates).