Shotcut is great if you never dived into video editing before, simply because it’s great for quick and simple video editing, it’s also fairly intuitive. But it can fall flat when you have specific (or more advanced) needs, like adding subtitles or specific effects, it’s doable, features are not fully the problem here…just that it can be a needless pain to use in such instances.
Kdenlive on the other hand is more complete but less intuitive, yet if you want something a bit more advanced it will do the job more than nicely.
So it widely depends on your needs and how far you want to delve into video editing.
I’d say if you wanna go crazy go for Kdenlive, if you want something simple go for Shotcut. If you want to start simple and go crazy later go for both.
They are both more than decent editing softwares, but Kdenlive is surely the best of the two, if not one of the best out there.
I’d add it’s usefull to know that in case of poor performance you can still lower the preview resolution or use something called proxies, to continue editing, not always ideal but it does the job. Performance also depends on your hardware, even without hardware acceleration, so the more horse power the crazier you can go with effects. Kdenlive also greatly improved (in my experience at least) regarding performances, even though hardware acceleration would still be a must.