Depends on what blocks you need to bias.
If you are doing amplifier/opamp, of cause you want your bias current to be increased with temperature, to compensate the drop of mobility hence gain of amplifier.
If you are designing oscillator, of cause you want your charge/discharge current to be independant of PVT, so that to have a constant charge/discharge to maintain oscillation freq over PVT.
If you are providing reference voltage for comparison, of cause it should be flat over PVT.
All in all, it is still depends on what blocks you need to bias.