Best free alternative in my opinion is a software known as Hitfilm Express. Hitfilm has key frames, great transitions and works smaller to premiere pro. If you are a beginner editor, i recommend ShotCut. Quite good if you ask me and i believe that it is good for beginners.
I'm using Lightworks at the moment. It's a tough program to get used to, but my pc setup is not great.
Hitfilm actually came up with an error message regarding my system specs when trying to run it lol. Shame really because it seems like a really good program to use from what I've seen/heard. I Tried Filmora, and all I got was messages about watermarks when it came to exporting (maybe I have the wrong version but it turned me off instantly). I know the most recent version of Windows Movie Maker will wait until you've fully edited your project, then try to charge you for the privilege of doing so and the previous version may not have all the features you need... unless you want to make a slideshow with sounds and text... Hey! here's some pictures from my holiday, set to music and the same transition effects you can get in Microsoft Powerpoint. I realise I may have got a little personal with Windows Movie Maker there… not a fan!
There's many programs out there, and if you're looking to do things for free or on a tight budget then you may have to make some compromises. For example, Lightworks will only let me export to 720p; which means I get the dreaded black edges in full screen when watching the finalised, exported video. Unless I upgrade to Pro of course, at a price, then I can do what I want apparently ¬.¬
Currently, I'm in a strong love-hate relationship with Lightworks, but the vast majority of the time, when mistakes are made, it's usually because I've been an idiot. More than happy to talk you through some of the bits I've learned so far in Lightworks if that's the way you end up going
All in all, it looks like you've got many, helpful, people who use different programs to do what they need to do. Just a question of what are your needs and what are you willing to invest in regards to time, money and frustration xD