It depends on what you want as a printer. You can go out and buy a fancy one with all the bells and trinkets or upgrade if that will satisfy your needs. You can fit a 4.2.7 silent board, V2 display and functionally have a E3V2 printer. Add better cooling fans, dual z axis drive and a CR Touch and if necessary an improved direct drive print head and you would effectively have an Ender 3 S1. There are kits available to increase the size of the print area. All of this would be cheaper then buying a new machine with these improvements. If that doesn’t do it for you then shell out the big bucks for a Bambo labs printer or equivalent.
Maintenance
Bed levelling springs are cheap and should be changed out regularly (maybe yearly) the original ones definitely need to go.
Nozzles are very cheap (brass) change them at the first sign of poor prints or on a regular schedual
Check the condition of the belts and wheels and replace if they look worn, these are also cheap.
Adjust the wheels so that there isn’t any play on the various axis’s, you don’t want any wobble
Check the extruder gears, they can wear out too.
Check the condition of the wires running to the extruder and hot end, they can wear/break from flex fatigue.
Give it a good vacuuming to get all the little bits of filament that gets into all the little cracks and holes and into the PW and MB.
All of these thing apply to most printers of any brand.
Any body have any other suggestions???