Up to now I workes with the Colorfabb PHA/PLA mix. It's very accurate and thus I found it to be very reliable. (Their shipping options of DHL-Express and UPS are a mess. Both are pure Business2Business courier services and are not fit for delivering to home addresses AT ALL.)
Now I ordered 4 large spools of the new nGen filament to use with mechanical parts.
It's supposed to be even more reliable and that's my primary criteria.
Olson BlockI'm also upgrading my Ultimaker II extended with an Olson block, a set of nozzles and a steel nozzle.
I hope to be able to do thinner layers with larger nozzles (at the same, minimum flow rate) and finer horizontal detail with finer nozzles as well as give copper-fill a try with the steel nozzle.