6. Sony UI
Sony’s UI for its devices is quite heavy and does slow down the devices. The UI is quite heavy but doesn’t really bring that many options which are actually helpful or can help you make the device reflect your personality(themes)
5. LG UI
LG’s UI has a flattened look to it keeping it in line with Android Lollipop but does come with numerous options to do similar things, eg: There are quite a few ways to multi-task: Slide aside, Dual window and the stock app switcher. Add in LG’s own boring voice assistant. However, it does provide some cool options like Knock on and a resizable keyboard and floating window notifications.
4. Samsung TouchWiz UI
Samsung’s Touchwiz has long been hated for slowing devices down but Samsung claims it has addressed these issues with the new version found on the Galaxy S6. The problems usually stem from Samsung stuffing the devices full of unnecessary features and excessive bloat.
3. HTC Sense UI
HTC’s Sense UI is the best Android skin by any OEM making Android devices today. Fast and intuitive, it enhances the look and feel of Stock Android and also provides good customization options including themes and BlinkFeed.
2. Stock Android
Stock bare bones Android is extremely quick as it is and gets the latest updates first. However, it contains all the available Google apps and relies almost entirely on Google Now which can get annoying. Also you need either a Nexus or an Android device to get your hands on the latest builds.
1. CyanogenMod OS
CyanogenMod is a custom ROM that runs on millions of devices around the world. It is basically a turbocharged version of Stock Android with the user being allowed to choose what apps he/she wants to use.