Thanks,
I will try the Polymaker, polyflex and polywood filaments. Polywood looks like a good replacement of Woodfill which has repeatedly ruined my nozzles.
I am planning to order the Colorfabb Copolymer as well.
Biome3D has given me the smoothest results so far, and prints most consistently. It has a lower viscosity when printing so layer bonding is better and overhangs print smoother, though small details like text tend to become a bit mushed.
I just ordered some Sun-Lu filament from Gearbest, together with a $60 laser engraver by the way. I will post some results as soon as I have them.
I sometimes have layer adhesion issues due to several factors, either the print bed not being 100% calibrated, the flow rate too high or low so the previous layer is too thick or thin causing inconsistencies in subsequent layers - then what can happen is that the filament only partially 'grips' the previous layer creating a very weak spot in the print, or the extruder not pushing the filament properly.