Past discussion: https://news.ycombinator.com/item?id=6693653

My personal find:

https://maximecb.github.io/Turing-Drawings/#4,4,0,3,2,1,3,1,...

While not as aesthetically pleasing as some, it displays a very complex behavior, with multiple spatial phases and Schlemiel the Painter's-style global synchronization. Might actually be worth a serious study.

Another one looks exactly like Conway's life, but than halts:https://maximecb.github.io/Turing-Drawings/#8,3,3,1,0,4,2,3,...

Here's a fork of the engine that allows you to see the transition diagram and control speeds: https://aesort.com/Turing-Drawings/#4,4,0,3,2,1,3,1,3,1,3,3,...