Well… From my experience octane is always faster and especially when it comes to complex+lighting and shading. It’s always also easier to achieve realistic looking materials (but this is maybe just my experience)
Anyways, if you guys want a neat testscene, Rawalanche made one here:
Use an HDRI
basic replicable shaders
no denoising
no GI-AO tricks (they tend to introduce very bad bias in more complex scenes)
fixed bounces
I was tempted to do this comparison myself but A: I have a lot of work and B: For my purposes I already know that octane does better and faster job.
Also keep in mind that clamping values might have different impact on performance and looks of each renderer and other things like scrambling (which is present in both renderers, just in octane is named coherent sampling) also works differently and might work in some cases better than others.
These comparisons might give some rough idea, but also remember it’s not always just render speed. Like I mentioned for me it is way faster and easier to get materials to look the way I want in octane, and in cycles I would always spend more time tweaking and tweaking and also octane has custom lut loader, better glare effects etc… Even if renderspeed of cycles and octane was identical I’d still would work faster in octane overall…
Artist time is always more valuable than rendertime, so if you have an important Paid work you might still wanna push things on renderfarm and pick renderer that makes YOU work faster.
I think LuxCoreRender is more similar to octane than cycles, different feature sets and the speed is not there but when it comes to providing realistic looking output with little effort, it is “faster” than with cycles… Again, unless renderer is extremely slow, or almost realtime, it’s just a personal preference IMHO…