What is the "best" cartridge a Technics 1210...

@lordvampire Grace HS-3 is lightweight shell if you want classic japanese vintage headshell, better one is Grace HS-5 carbon headshell with treated holes for the screws in the finger lift of the shell - that’s nice option to screw the cart from the bottom, not from the top of the shell (no nuts needed in this case). You can also look for the Orsonic AV1 shell (it looks like a catamaran boat :)

For the ultimate, but very expensive, look for the new ZYX LIVE-18B from Nakatsuka-San, i use this one with my Glanz MF61 cartridge. 

ZYX LIVE-18B looks impressive. How much it weights?

Btw my upgrade plan - I changed the mat, the cartridge, I have the discovery wiring, need to set it. I ordered oyaide silver headshell wiring.
The only thing left is the headshell and the isonoe feet. :)

And I think I'm ready :)

@chakster I replaced the wiring, and I must say the sounds is really impressive. I have a question though, now I'm in doubt. Do you unsplit the cables when you put them in the tonearm. Because I put them as they came (i.e. splitted, like in the picture).

No i don't use twisted pairs in my Lustre GST-801 tonearm for maximum flexibility. I use 4 single run of discovery tonearm wire. You can do the same for your Technics, but twisted wires also works ok, discovery wire is flexible, but not the most flexible.