Linux

I like Kdenlive and used it for a few months, but I also really like Lightworks. Lightworks is proprietary, but it's also a professional tool. Unlike DaVinci Resolve, it will decode and encode H.264/AAC, and most people don't need much more than that, though AV1 is also supported. The color correction tools in Lightworks are better than Kdenlive's and the cutting tools, while they take a while to get used to, are quite nice when paired with they keyboard. Best of all, Lightworks is a lot faster to startup, doesn't crash as easily and it's always responsive.

The most annoying part has to be dealing with licenses. If you use up your two licenses, you need to contact their support via email to shuffle them around. It's a great program, but this is super annoying. It also discourages you from purchasing the perpetual license because you don't want to get stuck in this situation. Mind you, their support is very friendly so I have no doubt they'd help you out, but it's an issue of needing to ask them in the first place. DaVinci Resolve's licensing system at least works perfectly fine, no matter what, or so I've heard. If you activate a new computer, it will just deactivate an old installation, and that's it. No need to wrangle customer support while everyone's on holiday...

The other professional option on GNU/Linux is DaVinci Resolve.

DaVinci Resolve is a very nice NLE at a very nice price, though proprietary. But $500 is a lot better than the $800,000 it used to cost. Annoying to install although fat-tire's containerization project is worth a look for easy installation. However, it doesn't work for my source footage, even with Studio. The free version doesn't support H.264 decode/encode or AAC decode/encode, which are the two main codecs you'll see with MP4, the most ubiquitous (and patent-encumbered) video format in the world. The Studio version supports H.264 decode/encode only with NVIDIA GPUs, but it still doesn't support AAC decode/encode. It can encode H.264 though, which will leave you with an MP4 file with no audio track.

To use DaVinci Resolve with H.264/AAC in a livable way, you need a NVIDIA GPU, you need to purchase the Studio edition, and you need to transcode your audio from AAC to something Resolve can ingest. There are scripts to automate this. Optionally, you should also purchase a third-party AAC encoder plugin for Resolve so you don't need to transcode again after rendering, assuming you're targeting H.264/AAC on render. If you're not, you can just render to Quicktime/PCM .mov.

As much as I love DaVinci Resolve, I kind of didn't think that was worth it for me at the time so I went with Lightworks which supports H.264/AAC encode fine with their Free/Paid licenses. I think I'll come back to DaVinci Resolve after 2028, when the patents for H.264 and AAC have finally expired (hopefully), and DaVinci Resolve includes decode support for AAC (hopefully). I might still use the Fusion tab for creating some VFX, but I'm trying to see if I can work with Natron first.

As for other NLEs:

• Cinelerra-GG: I quite like this editor, but damn it is particular and some things are just annoying to do. I've also heard it has color management issues... that was the main reason I stopped using it. That, and I can't actually get it to build anymore, haha. The manual is super amazing and beats out almost every other NLE mentioned here except DaVinci Resolve. It's not a bad read even for just generally learning video editing.
• Blender VSE: It works okay but the workflow is very slow and the lack of sequences (only projects) only makes things more annoying.
• Openshot: I'm not a fan of the interface and found the workflow, at least initially, slow.
• Shotcut: Seems nice enough but it didn't work for me. I forget why.
• Pitivi: It crashed the instant I tried working with 4K footage.

Edit: Olive is nice too but very early stages. Color tools are very basic. And unfortunately development is winding down.

Ah...sorry, I just realized this probably isn't the response you're looking for. But I've spent a lot of this week trying to find a professional NLE on GNU/Linux and that was what I came up with. For the record, I'm a GNOME user and I liked Kdenlive the most out of free software NLEs. I'm looking forward to the new improvements to come from the fundraiser to improve workflow!