Honestly, having all 3 is the best choice.
What Hulu has, Netflix does not and vice versa. What Amazon has the other two tend to have but Amazon has access to stuff the other 2 do not. Cherry on top benefit is Amazon plus gives discounts and shipping and other goodies for stuff you buy on amazon (as well as free books, music, etc).
All 3 together are, per month, less than 30 bucks. (avg $8 each per month).
So... you have your free airwave TV plus internet tv service (eat your heart out cable co's) and the extra amazon goodies.
All in all a much better deal than the idiotically overpriced $50+ a month 'basic' cable tv packages that claim to offer 130+ channels of which they count the 40 something free air channels, 20 something are sell-you-stuff channels and the rest are a mix of crap you never watch... all just to get two or three channels you do watch.
I use Netflix for PBS/NOVA documentaries mostly as well as some tv show series (like BONES). Hulu and Amazon let me watch a lot of movies...and I get my anime for free from crunchyroll and anilinkz websites.