FAQ: "I just bought a ECC, what upgrades do you recommend?"

YMMV, but here are my suggestions, in order of importance:

1. Good surge protector. Better yet, a decent UPS (rated for at least 1500VA).
2. Dedicated heavy and sturdy table, if your space / living situation permits. The heavier and sturdier, the faster you will be able to print. No wheels please. The ideal printer table is a huge solid chuck of concrete, everything else is a compromise.
3. Filament dryer. Don't bother with the "latest and greatest" unless you plan on running AMS; a good ol' Polydryer will do for literally everything, including PC and PA.
4. A good set of digital calipers and/or a micrometer.
5. A multimeter, if you don't have one already.
6. A set of Wiha or Engineer brand metric hex drivers for working on this thing.
7. A few spare hotends paired with different size nozzles.
8. Spare nozzles.
9. 6mm preset torque socket driver for nozzle changes. Ideally, you'll just get an adjustable torque screwdriver and convert Nm into in-lbs or whatever. Get one with 10 in-lbs or lower on the low end of range.
10. A "sampler" sized spool of white nylon for cold pulls.
11. Some kind of filament storage solution. I suggest bags + vacuum pump + dissicant, but a lot of people just store it in extra Polydryer containers.
12. Spare build plate or a few. Personally, I use an off-brand PEI-coated sheet that is textured on both sides, unless a project requires mirror finish on its bottom.

Got any more ideas for the list? Please share!