For that kind of flying, I’d lean towards the engine, provided the installation and maintenance records are good. I’d rather have a fairly basic panel that covers what I need than pay for equipment I barely use.
I’d price up the changes I’d actually want on each aircraft first. “Better avionics” could mean a radio you’d use every flight, or an expensive display you don’t particularly want. Those would affect my decision differently.
That’s a useful distinction. So perhaps the comparison should be what each aircraft would cost to get into the condition and configuration you want, rather than which advert has the longer equipment list.
What would you consider essential in a C42 panel?