FYI, my little farm runs exclusively on Ender 3 V2.
The roller guides make them basically maintenance free.
I have replaced the springs with cheap silicone spacers.
For the extruder, I use full metal dual gear ones from the CR10 series. Those last about 1000h of printing and cost around 15€... Maybe they last longer if properly greased from the beginning and if you're not running linear advance... Which I stopped since prusa slicer allows limiting the change of filament flow.
The extruder is now from E3D ... A revo micro... The revo CR should be a even smoother mod.
The classic nozzles always started leaking after some 100h of printing.
If you are okay retightening, the full metal hotends from the CR10 series are fine. Depending on the print temperatures, bi-metal heartbreaks can help.
For PLA, a stock full-metal hotend is fine.
Prusament PetG benefits from bi-metal ones.
Lower temp PetG (eg Extruder) is ok with the normal ones.
The stock hotend is shit. The PTFE tube pressed against the nozzle gives you really a bad experience compared to the full-metal one.
ATM, I'm also converting one printer to a E3D Hermera. This includes dual Z because the Hemera adds quite some weight and the filament pulling force isn't neglectible either.
This is conversion is simply because I have an upcoming application for soft TPU.
Oh, and I have mounted CR touch probes... Very smooth upgrade thanks the brackets and the ready made cables
The last thing I'm now experimenting with is the build surface.
The glass bed is fine for PLA.
PEI film on spring steel is ok for PetG, but wears relatively fast (it "chips" off).
BuildTak is ok for PLA on a magnetic bed.
ATM I'm testing PEI powder coated spring steel sheets from Creality. I don't have too much experience up to now, but this is really really really promising. Howevery, you should be ok with the texture.
FR2 and pertinax is coming as well. I tested this in the past and it was fine. However, I'm not sure how well it will do when combined with a magnetic bed.
In addition, the textured PEI beds are really nice so far. If they last 500h (thats about 100 prints on the same position on the sheet) of printing, I think I may skip these alternatives.
Regards