I gotta say, I admire the specificity of this question!

I don't even remember what my previous phone's looked like. I'd have to see a bunch to pick a favorite.

I remember loving my bright yellow Nokia windows phone, and I also remember having phones with charging animations that were particularly cool. I don’t know if they were the same device, but let's pretend they were.

The current iphone one is boring. I miss the skeuomorphic battery that was last seen in IOS 6.

This question gets a lot more complicated if you allow custom firmware discussion, e.g. of Android phones.

My Galaxy S3 had a nice one, but it almost certainly was not from the stock firmware. I remember a glowing ring that would fill up.

the pre-iOS 7 one is my favourite, since it replaces the wallpaper with battery and makes it very obvious the phone is charging

there was a jailbreak tweak called battery doctor pro that adds some useful info on the charging lockscreen, i want it back