FilmoraGo is a video editor app by Wondershare. It's easily one of the best video editor apps. This video editor packs a whallop. You can do the basics like trim and cut, render, and that kind of stuff. It also includes the ability to play in reverse, do square videos (1:1) for Instagram, and 16:9 videos for YouTube specifically. It also has support for things like slow motion, transitions, music, overlays, and more. It's not half bad for what you get. There are in-app purchases that add to the power. However, most of the features are, in fact, free.
Adobe Premiere Clip is one of the big names when it comes to video editor apps. It has a laundry list of features, including the ability to auto-generate videos using your images and video if you don’t want to do it yourself. If that’s not your thing, you can edit your video manually using a variety of tools, effects, and music. The app boasts that you can use your own music but some users have found this process to be difficult. It does sync and work with Adobe Premiere Pro so you can start a project on one and continue on the next one. However, you'll need an Adobe Creative Cloud account to make all the syncing work.
OPlayer Lite is currently one of the best video players for iPad. It has excellent support for almost all formats (the latest update includes MKV support too). There’s an AC3 issue with the current version though — still, a far better player than many others out there. The decoding can be particularly tricky with other apps, but Oplayer appears to handle it quite well.