WRT chain, a good front fender - and a good mud flap - is more important than a rear. It should come down close to the ground. That keeps the rooster tail of road grime drawn up from the front wheel from hitting your chain and chainring. This is the one on my winter bike:

(Yes, it is a piece of an old boot. Good rubber, long lasting)
I use hot wax as a lube on this one, get about 500 km between applications. I’m alternating between two chains and will hit 5000 km at the next change. No obvious drivetrain performance yet. This is in Sweden, so there’s plenty of sanded/salted winter riding.
For various reasons, it’s the only fender-equipped bike I have that’s in order at the moment, so it has the summer wheels on in the pic.