What is more accurate: magnetic anti-skating, or barrel weight attached a fishline?

Dear Ralph (Atma-sphere), I beg to differ slightly with your analysis. For a typical pivoted tonearm that is mounted such that the stylus overhangs the spindle and the headshell has an offset angle, there will always be some skating force, even at the two null points on the surface of the LP, because at the null points, the headshell offset angle per se will still be a cause of some skating force. Although the cantilever/stylus is, at those two points, tangent to the groove, the tonearm itself is not, due to the headshell offset.

So you're saying that despite being perfectly tangential, skating forces still exist? IOW that they are generated by the arm and not the geometry of the stylus in the groove?

One way of demonstrating this is to raise the arm, stare at the cartridge from the front, wrap an elastic around your cartridge body (not the stylus/cantilever** ) and pull straight out toward you.

** Not responsible for any beheaded cartridges. 8^0

Hi Henry - hope you are enjoying your winter.
Its been terribly hot/humid here. Been staying at the lake up north (for me) pretty much full time. Sunnyjim thanks for letting me catch up on your thread.

"HOOK. LINE, AND SINKER" ANTI-SKATING"

funny...good one. :^)

I never expected such an impassioned discussion over the anti-skating used on many turntables.

Myself I have never met any audiophile that was not passionate. And vinyl guys (not really gals from my experience) are over the top.
I mean this in a good way. After all we could be into other things causing no good. We are not hurting anyone.

Ralph, I am saying that when the cantilever/stylus is tangent to the groove, the friction force generated by the stylus to groove resistance has a vector directed tangent to the groove, too.  But because the headshell is offset with respect to a straight line drawn from the cantilever to the pivot, there will still be a skating force due entirely to the headshell offset angle.  Interestingly, if you use an "underhung" tonearm (no off color pun intended) with zero headshell offset, then there can be only one null point on the surface of the LP with respect to tracking angle error, but at that one null point, skating force will also be zero, because the forces will line up with the pivot.

TLDR (too long, didn't read - so some of this may have been covered) ...

In general (because especially with anti-skate, there are no hard and fast rules), the smallest bit of anti-skate has worked best for me ... definitely err on the side of too little (to retain dynamics) rather than too much.

With some unipivots, a touch of anti-skate can have a secondary positive effect of stabilizing the arm a bit.

Gravity vs. magnetism?  Both are constant forces, and you can engineer a system so either one works (progressively increases as you track toward the inner groove), or alternatively is sub-optimal.

Cheers,
Thom @ Galibier Design

Dear @sunnyjim : My response is: none.

As a fact exist no one AS mechanism that's accurate. It's i9mposible to have it in a totally mechanical imperfect medium with a pivoted tonearm.

Any one of us can say that we hear/listen better quality perfomance level with out any kind of AS or with AS at maximum or minimum but in all cases we are far away from true.

We need always AS ( if we use it or not is a different matters. ) problem is that what we can choose to do it is non-accurate including what @almarg  posted  and I refer to him with all respect.

Subject is very complex because we have to deal: with different recorded velocities at each LP and on each LP those recorded velocities changed at random at different place/distance in the overall LP recorded surface, we have way different compliance cartridges and this means not that we have low/medium/high compliance but different cartridge compliance figures over the whole compliance range that exist in all cartridges!, cartridges has different stylus shape tips and different level of quality of those stilus tips because some one are better polished than others and all of these has an influence of the AS needs ( I remember that in  one of my AT tonearms were 3 alternatives of AS depending of the stylus shape. ), off-center LPs ( all LPs. ) needs different AS, even the warps in LPs ask for different AS because at each single warp VTF change, exist tonearms that use damping oil like many unipivots or the SME or Triplanar or Townshend, etc, etc.

AS level is affected with each of those non predictable changes/parameters and some others.

So, an accurate universal perfect AS mechanism is non-existent yet.

Regards and enjoy the music,
R.