I’ve used both Downie and 4K Video Downloader+ for years, mostly for YouTube.
Both work very well, and have simple and easy-to-use interfaces. I think for most people, Downie would have a slight edge in usability terms. I tend to prefer 4K Video Downloader+, but it’s for mostly subjective reasons: I occasionally need to change the resolution or format, and I find it easier to make the tweaks in 4K VD+ (without having to search around re: how to do it).