Yeah, "best" questions must include "for what" to get a reasonable answer.
Temperature/velocity stability as provided by Varget and to a lesser degree by IMR 4064 comes at the cost of high/low metering challenges (not an issue if weighing charges) and to a small degree, long-term powder stability, and with in general higher flame temperature which can wear the throat a bit faster than...
Spherical powders like WW 748 meter very well and have lower flame temperatures but can go 100 fps or more slower at 30°F or so compared to 100°. It is easier in manufacturing spherical powders to neutralize the acids, and stabilizers last longer before being depleted with them, so those powders often have a longer shelf/loaded ammo life than extruded powders. However, I do not know whether the newer-tech "green" tinted powders like Varget and Hodgdon's other Australian offerings share this characteristic with the rest of the extruded powders.
With the right loads, all of them can be very accurate on target.
For a bolt gun, burn rate generally matters very little unless you're after lower flash and cannot use a flash suppressor (my favorite solution). I believe that faster burn rates flash less but there are too many other gas/temp variables for a hard and fast rule. Despite internet rumors to the contrary, the slowest powders almost always give the highest velocities even as barrel length gets shorter.
For a gas gun, burn rate can matter a lot with the newer tech. M14 types cannot use max-pressure loads using RL-15 and 175-gr class bullets without exceeding the 14,500 CUP max port pressure (14-1/8 or 3/8 inches from the boltface but about 12.1 inches of bullet travel) for its White mostly self-adjusting/compensating gas system (superior to the FN-FAL adjustment system in my limited testing for lower port pressures). Sorry, I haven't been able to locate reliable port pressure specs for large-frame ARs).
So, the best answer to the question as posted is:
It depends.