Electronics plays a good role, in particular if you want to build a delta printer the processing speed is a relevant factor. However I found myself well with a Arduino Mega based board and drv8825 drivers, as a basic approach for a desktop size printer. I have a Megatronics from RepRapWorld, but now they make the UltraTronics, which should cover most of the processing needs of a 3d printer. Many other broads around, but prices for a good one are roughly the same unless you are looking for something super special, such as the GH speedy board which pushes insane speeds, but is well far from cheap.
Almost all stepper motors work with a 1.8deg step. The torque needed depends on they weight they need to carry around. Nema17 the most common choice, preferably low inductance. If you go to Nema23 for a big printer, the drv8825 won’t be enough and you will need something more hardcore to drive them.
On the other hand mechanics is what decides the ultimate precision. Pulleys and belt are relatively standard, but the quality of rails, carriages, smooth rods and bearings really make the difference. Same for the leadscrew (or ball screw) and relative nut to get the precision.
For the hot-end I think that the E3D V6 is one of the best around. If it is not an original E3D it won’t work anywhere as nice.
For the feeder, I have a preference for direct drive (as opposite to bowden), but actually all my machines are bowden and work well. Also bowden makes the printer design simpler, until you look at the E3D Aero Titan.
Disclaimer: I don’t work for E3D nor I have any personal direct interest, just thing they make good stuff.
If you want to go bowden all the way, then the Bondtech feeder seems to be the golden standard for that. Almost never felt the need for one… almost… so never actually tried.
Talking firmware, there are several around. I only used Marlin and it does all I need it to do, but others with more experience might disagree.
Talking slicer there are also a few options: the two most common options are Cura (Free) and Simplify3D (Paid). I prefer the second, gives me much more control on all parameters. I have heard good things about IdeaMaker (Free), but never actually used it.
Sorry for being so generic, but there would be so much to say about the topic and it is impossible to say it all. With more specific questions I’m sure the community will help more.
Cheers
