Trying to settle on a video editor to use all the time, I tested a few over the last couple of weeks. Rather than typing out a full new post, here are the notes I'd made for my own purposes, with a few extra notes put in for clarity. So I still haven't really found one, VideoPad has the nicest UI, useability and effects, but the one problem mentioned below kinda spoils it for me.
SHOTCUT: Correctly deals with frames, but some of the effects are terrible. Especially the old cinema type. "Scratches" and "Sepia" are appalling. Editing the time line is pretty much unuseable with it chopping things off by itself, bouncing and jumping around making it impossible to put a clip exactly (or even remotely) where it's wanted. Had several full crashes in the space of a few hours.
DAVINCI RESOLVE: Seems to need an absolute beast of a PC to run without it being slow and laggy. I therefore can't test it properly. It does seems to correctly deal with frames but it can't even play a single, simple clip on my machine.
OPENSHOT: Frames are numbered 1 to 25, or 1 to 30, instead of 0 to 24 or 0 to 29. I couldn't find anything on the net about this, and I couldn't find any settings to put it right. It's therefore discounted on this one item alone. I can't begin to imagine the number of problems that would cause down the line when editing.
VIDEOPAD: The effects I tried, whilst sometimes lacking much in the way of customisation, at least look good. Old cinema effects are excellent. Deshaker is very effective. But I'm really struggling with the timeline. With a 30 fps clip in the timeline, frame forward and backwards result in 000 033 067 100 133 167 200 (which is correct). But counting down gets 200 167 134 133 100 067 034 033 000 - Which would cause nothing but headaches when editing using a hardware controller (or even just the keyboard). The display should really be in frames anyway. Or ideally, both. Due to this, it sometimes also gets the next/previous frame display wrong, occasionally showing current and next as being the same frame. Which is kinda useless. If a 25 fps clip, and a 30 fps clip are both put on the timeline, it gets even worse. This is a massive shame because I really like the rest of it.
If NCH fixed this issue, I'd go for VideoPad without hesitation, but I've been reporting this (or similar, closely related bugs) since about version 5 (!) seven years ago. It got meddled with from time to time, changed, but never fixed. Just changed one bug for another. Either I'm the only one who considers it a problem, or NCH themselves consider it trivial. Either way, I can't use it. Massive shame.