I've been an AOSB user for a long time now, it's a great kitkat rom and does almost everything I've wanted it to do with no issues at all. I just recently wanted to use my phone to watch movies on my HDTV but apparently AOSP roms won't let me do that, at least not with the hdmi cable I already own. Since I didn't want to spend any money on new equipment that may or may not work I decided to try out touchwiz again, I haven't used it since 4.1.2. Some things I'd completely forgotten about, so I thought I'd put my opinions here while they are still fresh in my mind. This might help somebody who is afraid of trying something new, in either direction.
AOSP/CM - 1. Fast. Just opening and switching apps it is noticeably faster than TW.
2. light weight - the roms are generally only maybe 200 mb's and backups generally are quicker.
3. themes - for roms with theme engine you have hundreds of themes at your finger tips, and it only takes a few seconds to switch themes. If you get bored easily looking at the same thing this is a major plus.
4. Depending on the rom you have options, tons and tons of options.
5. again, depending on the rom, you have HALO, multiwindow, active notifications, omniswitch, etc.
BUT...negatives include no wifi calling, signals seem a little worse, and some things (like HDMI out to tv) don't work as well or as easily as TW.
TW - 1. It works. Well. I haven't found any issues in daily use with it.
2. Many of the modifications and options found in AOSP can be added to TW using xposed, plus some TW roms have these options built in.
3. Battery life seems better, with or without custom kernels. At least in standby. With cm I'd lose about 5-6% in 8 or 9 hours overnight, with TW and the same apps and options I lose maybe 3%.
BUT...TW is slower. Not much and not in everything but when it does lag its easy to get annoyed after having used AOSP for months. Maybe the annoyance will go away once I get used to it?
Also, this is just personal opinion but I feel like the settings in TW is just a mess. The "google" way of arranging settings needs a little work but overall I think it's easier to use than samsungs version.
I know this isnt' anything new for most of you but hopefully for somebody who is on the fence and not brave enough to switch from one to the other this will help.
Also, if any aosp/cm users have any help for how I can hook the phone to the tv I'd love to hear it.