What are the features you really appreciate in Fusion?
I'll start with 5 so the list don't get too big
1) Ability to open two Fusion instances (non-steam version only I guess?), copy object and events to another fusion instance. Rename the object. All the code will be updated with that single rename. Copy back to the first instance. Really easy to duplicate an object with similar events.
2) Fusion will not get lost in the values name. If you have the default "Alterable Value A" in another instance but copy the code to the first instance that have "ID" on Alterable Value spot, the code will be updated despite the fact their name is different.
3) The icons in the Event List Editor. So much easier to read the code and get to know the object we are dealing with.
4) Reference by number: Global Values, Directions, Frames all can be referenced through numbers.
5) 2.5+ Only. That beautiful Find All. Despite having thousands of lines and events, the find all can get you quickly through events, sound, objects, loops, comments. Whatever you need to find.