With all of the hype about which printer is best, a large elephant in the room keeps getting overlooked… The skill and knowledge of the operator. An expensive machine is not needed to produce high quality prints, and it definitely does not guarantee high quality results either.
As proof of this, I have a scratch built Kossel design that easily prints on par with the best that I have seen from Ultimaker 2 machines. Of course, those Ultimaker 2 prints were made by someone who also knew their machine. One big difference is that the Ultimaker 2 costs about $2500, while I built my Kossel for around $400.
I’m not saying that the design of the machine is not a factor in print quality. It is. For someone who is on a quest to produce the highest quality parts achievable with an FDM type machine, you need to start with a machine that has certain characteristics.
Foremost would be a rigid frame and gantry which is capable of accurate and repeatable results.
Next would be a machine with low moving mass, such as a Delta, coreXY or perhaps an H-bot.
Also very important is an extruder system which has a small thermal transition zone which is highly resistant to jamming and uneven extrusion rates.
Lastly, your print quality really can benefit from a high performance controller (such as a 32 bit board running Smoothieware) and high quality stepper motor drivers which are properly adjusted. The ultimate stepper motor drivers would be one of the newest generation of DSP digital drivers that are silky smooth and silent across the entire operating range. They exhibit no detectable resonance behavior and when coupled with a low mass extruder system, the speed and quality can be very high.
With all of these advantages, the operator still plays an even bigger role. They must have a very good working knowledge of how to slice parts (a good slicer also helps a lot). They must constantly be aware of little things that can have an adverse impact on print quality - such as how to detect and correct a slightly clogged extruder nozzle which is not pumping filament straight out with absolutely no curling. The operator also needs to know when and how much to use a layer cooling fan. The overhang areas of a part can be enormously improved by someone who can setup their slicer to give just the right amount of cooling in the critical areas of the part. Printing speeds and directions, infill patterns and densities, extruder and bed temperatures are all just a small number of variables that have to be skillfully managed. The knowledge of how to do these things normally only comes with many long hours of trial and error.