Lulzbot and Ultimaker

The AO-100 is very fast too. You can crank either of them up. Print quality decreases as speed goes up (generally), but this is true of all printers.

I think Ultimaker is a great company, but I am sure there are issues with their printers as well. We have built one in the past (an early generation). The bowden design wasn't very good, at least not back then. It will be interesting to see how it prints for you. The Bowdens are generally better at making something that is like a vase or whatever, that doesn't require a lot of travel and retraction, since the bowdens dont retract well. Perhaps they've solved that in the interim though. Also, their build volume is much smaller than the taz, it is made out of wood (not even very strong wood, at least the version I had), it doesn't have a heatbed (standard?), etc. Anyway, I think it would be a good exercise. Undoubtably, one printer will be better at one type of print, the other at another. Also, "show me the code". They do quite a bit of free/open work, which is awesome, but the full designs for their printers aren't online, afaik. But this is true of most "open" companies (though most do far less than Ultimaker!).

There are few people that have posted details about using a variety of "open" printers. Here is one, where the guy has two Lulz and two Ultimakers, plus other machines: http://makezine.com/2013/04/25/being-a-printer-master-managing-mass-printing-in-a-makerspace/

That said, if I wanted a non-Lulz assembled printer, it would probably be the Ultimaker (then I'd badger them for the source!). ;)