The noise characteristics of drives vary from model to model and sometimes from samples to samples.
I have no reason to distrust SPCR's measurement and they say that some 3.5'' hard drives are about as quiet as quiet 2.5'' drives if you can suspend them or otherwise dampen their vibration and seeks. The quietest drives SPCR measured are WD drives which I have no experience with. But no 3.5'' hard drives I've ever heard comes close to a quiet 2.5'' drive noise-wise.
From a noise perspective, what's nice about 2.5'' drives is that you don't need a lot of work or space to silence them. But they have disadvantages of course.
If you want 1TB, you might have a problem: in my experience, 2.5'' drives tend to get louder as the platter count increases. They also get less reliable. So while I think that a cheap 2.5'' drive would often be a good choice if you don't need a lot of capacity, 3.5'' drives would be the natural choice if you want 1 TB or more.
No drive should "require" alignment. But they'll all perform better if aligned properly.
WD might have a bug (or a "feature") that makes the improper alignment worse than it should.
It's not terribly difficult to align a partition properly anyway.
that's something I wondered since a 1tb 2.5 drive might have more platters than a 1tb 3.5 drive, offsetting some of the quietness.