First thing I noticed was the cell standby battery drain which I have seen on numerous lollipop devices and roms. It was draining the hell out of my battery but I found out it was an easy fix on T mobile. Disable Voice over LTE by going to dialer app --> More --> Settings --> Voice over LTE settings --> Do not use. No more cell standby battery drain!
Adguard- Im used to using an adblocker app but most of those require root. Adguard creates a VPN on the phone and filters out all of the ads from web pages and tracking info from your web data. Speeds up any browser and helps battery life.
Package Disabler Pro- Usually disable or uninstall unwanted apps with Titanium backup, but this app can do those same functions without root! I disabled 178 system apps and bloatware. Phone performs better and battery life is amazing (On pace for SOT of 9-10 hours with brightness on auto, battery saving location settings - wifi and cellular only - when Im not at work where I have really crappy signal all day. I will give a full battery life test this weekend).
Next thing was getting as close to the stock look and feel as possible. I got the Dark Material Theme from the Theme store before disabling the Theme store . I installed Action Launcher but Nova Launcher will serve the same purpose, and disabled the Samsung Home Launcher. Unfortunately when you switch the launcher, you go back to those cartoony Samsung icons. No good. So I installed Glim icons There are many material design icon packs and the icons here arent strictly like the stock ones but they are very nice and the nice thing is it changes out most of the Samsung icons for the apps you will want to keep around, like S note and the Galaxy Apps (I bought the paid version which I think has more icons). Now the software looks amazing to go along with the hardware. And I was concerned about battery life coming to this phone but now, to my surprise, battery life is actually better than I was getting on my Oneplus One on Lollipoop. May not need root after all.
WARNING: DO NOT USE ULTRA POWER SAVING MODE IF YOU HAVE COM.SEC.ANDROID.EMERGENCYLAUNCHER DISABLED - YOUR PHONE MAY FREEZE AND BE UNABLE TO BOOT AND YOU WILL HAVE TO DO A FACTORY RESET. THE REGULAR POWER SAVING MODE IS OK.
I attached some example xml files. There is a "basic" xml file with around 150 disabled apps where I only disabled the apps I am sure of what they do, and mostly left apps and services that shouldnt run in the background most of the time anyway. This package preserves the most functionality and gets rid of the samsung fluff that you probably dont want and gets rid of most of the things they use to spy on you.
There is also an "extreme" version which I would say is still somewhat experimental but has been running great for me so far. BUT USE AT YOUR OWN RISK IT MAY NOT BE COMPATIBLE WITH ALL APPS AND SETUPS. It disables around 200 apps!!! I attached screenshot of battery life I have gotten with this configuration. This is my own personal configuration so there is some minor functionality missing because I only left the things I felt were important for how I use the phone. If you like, you can import this and work backwards, enabling the things you want if you kind of know your way around the app.
I also am posting a screenshot of the 250 apps and services you can disable safely without crashing your phone or creating major issues. Probably. Hopefully.
HOW TO USE XML FILE: You have to download and unzip the xml file, put it in the /storage/emulated/0 section, open the app and select import xml file from menu. You will need to re-enable the stock LAUNCHER, CLOCK, CALENDAR, MESSAGING APP AND KEYBOARD, or replace with alternatives from playstore like I did if you use extreme configuration. You will also likely get a message saying you have modified your phone without permission or something when you try to do a System Update (at least thats what I get on the T mobile version). When there is an update or you want to check, you should use the app to export your file to preserve your settings, then re-enable everything, reboot the phone, check for update, then import your xml file again to go back to how you want it.
To update if you're coming from a previous configuration, first go into menu and enable all disabled apps then import the new XML file.