The values here is not absolute, these printers is created in a RepRap fashion so many variations will exist, also they are changeable. A Mendel can print with 1.75 mm and so forth. As always when starting or you want to upgrade you ask what to go for. This is off course a question of economics as well as it is a question of technology. Ease of build is in my mind a question to often forgotten, even if it is rely fun to conquer a complex build it is by far more satisfying to join the ranks of printing enthusiasts. Thingieverse is full of extremely good models you can download and print. So in my mind, ease of build is important as well. That brings us back to the documentation, that is in my mind the key!
By far the best build documentation I have ever seen is for the DURBIE, I don't like Wiki:s and sites like this for documentation as such. I want something I can follow locally. So a compromise I am not to fond of either is a PDF document. My own experience with the Mendel V2 is good, but I am very experienced in reading drawings so for me that is not a problem. But if you are not comfortable with 3D drawings that build is a bit of a uphill struggle. The Orca printer is not truly a 100% REPRAP printer even if it is based on that concept. Anybody and everybody can cut and create the Orca frame ( aluminium sheets ) but the norm for most of these printers is the threaded rod and PLASTIC solution.
I also find that there is a good sound idea behind a printer that can print it's own upgrades as well as service parts and spare parts for it self. You can also print out the parts for a friend and lower the cost to only what you can't do your self like motors and electronics.
For the actual printing with a HUXLEY with our PLA we had great results with this setup.
Use it as a start guide to get better prints faster:
Printer: eMaker Huxley First generation.
Nozzle temp: 155c (Default on eMaker Huxley = 200c).
Bed temp: 60c (Default on eMaker Huxley = 90c).
Extruder steps: 800/mm (Default on eMaker Huxley = 900/mm).