Firstly, I've never purchased or implemented templates in any of my After Effects work. I think this is important because while I may borrow from other sources for inspiration, all of the effects I create are made from scratch using techniques I've developed from time spent in the software.
I make use of third party plugins and scripts within After Effects. This is always done with intention, keeping the following criteria in mind:
While plugins can be used merely as a crutch or shortcut, third party community development is a key component of what helps keep After Effects relevant in the design community. Keeping on top of the latest updates from these developers is important to staying up to date on creative and technical possibilities with the software.
After Effects is the go to tool for procedurally generating titles for projects. In addition to titles, I've used After Effects for light compositing as well as motion design work by porting in vector designs from Illustrator or Affinity Designer. It's also ideal for creating animation to be used in interactive design, such motion elements used on this portfolio site. I have some familiarity with expressions and have also built templates for clients to use in After Effects or with the graphics panel in Premiere. It's also my favorite software for 3D or 2D motion tracking with effects.