Interesting how the almost 5mm ruby ball tip exhibited even less tip friction on standard glass than the spiked carbide tip did on carbide, when the RPM is sufficiently high.
When the RPM is high, yes, but, what it matters, it is when the angle of tilting is large. The best condition for the ball tip is when the top is quite tilted and the spinning surface has a thin oil film; the problem is that, while spinning, the top rises so the tip friction increases.
The oil, which gives the advantage of a decreased rotational sliding friction at the tip, (and of the total friction at the tip), also gives the disadvantage of an increased rolling resistance, which, in turn, accelerates the rise of the top.
By the way, grease used as a lubricant, which makes the rolling resistance even higher, makes the rise even faster.
If you find a way to use ball tips and oil without making the top to rise, you could have found the way to have the lowest average total tip friction for a top.
Of course, there are too many differences between the tops and bases you used and an EDC top, mass being an important one, so I will be well served experimenting with material/tip shape on my own.
In this test I always used the same top, with the two different tips. The spinning surfaces are different but the spiked carbide tip digs too rapidly a concavity in the glass, not even a ruby base is wear resistant enough for it, it needs the carbide base; and ball tips wear more rapidly on a carbide base so I normally use them on glass, not on carbide.