I've never used Hulu in my life, and so can't comment on it.
Compliments:
Netflix - I love their content, but find myself running out of stuff I enjoy on there, once I've gone through new season releases and their originals. Though, that's happened more so since I swapped from UK Netflix to US Netflix. Maybe I should just use a VPN

I also love how clean the player is and the skip intro option is a GODSEND.
Amazon Prime - They're getting some pretty good prime originals, and I really like the x-ray (I believe it's called) feature where you hover and get shit tons of info like actors/music playing/trivia etc. The jump forward/back ten seconds option is another GODSEND.
I'm totally 50/50. I kinda wish everything that's good about the two would just merge. I use them equally.
Complaints:
However, Netflix does keep changing their menus for searching for shows. Like, when you click on a genre, it lists what's on your list, what's popular etc. I wish that crap would go away. I just want an alphabetical or ranked list, not what they're suggestions are. I rarely find their suggestions are anything like what I'm after. I also don't like that some of the genre options, I use to use all the time, have disappeared. In addition, they now only let me search TV shows OR movies - can't search both at the same time. These are my niggles with Netflix, which will probably change in 6 months when they update it all again - which they do very frequently it seems!