Tonearm suggestion for Garrard 301 schedule ll oil bearing?

I've 4 Jelcos. The 12" 850L is very detailed and etched and tracks my Decca cartridges well. Bass timbre definition could be a little better with alternative headshells. The magnesium HS25 standard one is fine but bass is better on the Yamamoto HS4. However, like most carbon fiber damped the top removing the extreme detail. 

I have not heard the GM2 and it’s always on my list but I have heard it described as a little detail shy in the top end.
I’ve heard the same about the Schick.
Which leaves me with the Jelco. I don't think you'll regret the 850/950 and they'll hold their value. The pink cable is fine.

With an appropriate plinth you can use any tonearm on the market with your Garrard and if your 301 is meticulously serviced (and even modded), the better the tonearm the better the sound. Check out my profile and system. I have not tried every arm out there but quite a few and I am a fan of the Reed 3P.

From an aesthetic standpoint the SME is classic. I do not know the groove master very well but I do not trust Titanium in a tonearm. Unlike aluminum titanium rings like crazy. It is also harder to machine. Maintaining tolerance is more difficult which is why you do not see many of them out there. If you have to have a 12 inch arm then look at the Schroder CB and the Reed 2G. I personally prefer the Schroder but the Reed is also an excellent arm. Both are neutral balance arms with their vertical bearing at the level of the record. Both have frictionless magnetic anti skating. Both are lighter than both the SME and the Groovemaster. This will result in less distortion with most cartridges.

Thanks to all for your response and advices, they are very useful for me. I’ll definitely check Schroder CB and Reed 2G tonearms. Seems like everybody loves SME 3012 series l or 3012R probably  because of the stainless steel arm wand, the problem is that so hard to find lately.