the 3dr is great only if you get the parts printed perfectly .. If you have any warp or lift on the parts or your printer is not perfectly aligned you will have a mis aligned frame . Were as on the kossel even with mistakes in the print you can adjust the frame. Also for the kossel if you decide to go bigger later you can use the same printed parts again.
IMHO avoid the spectra line if you can .. I do have it running on my 3DR but it was a pain to setup.
IMHO avoid the spectra line if you can .. I do have it running on my 3DR but it was a pain to setup.