Recommendation for Cartridge for Technics SL-1200G?

If you're looking for ART-9 make sure you're buyin' from the official distributor (not from grey market dealer), so you can get factory retip in Japan for very reasonable price when you will need it. 

In general for Technics tonearm you have many cartridges to choose from brand new to vintage heritage. From MM/MI to MC. 

Just don't buy a low compliance cartridges and don't buy very high compliance. 

I would recommend the Victor X-1II (Beryllium/Shibata) or its cheaper alternative X-1IIe (Titanium/Elliptical). Both are great, the stylus on Beryllium cantilever is better. Any of them in NOS condition worth the investment. Even if you will buy an MC it is nice to have an MM alternative to compare one to another. 

On LOMC side the Dynavector DV-17DS with Diamond cantilever and Micro Ridge diamond is great, the mkII version is even better. 

Two posters recommends cartridges with Conical Styli, this is to be honest the worst stylus profile on the planet, no matter on which cartridge. Conical tip has the shortest life-span and can't extract music from the record grooves. This profile must be avoided by anyone who is looking for high-resolution and accuracy. 

Also a low compliance cartridge on SL1200G is not a good idea, only with very heavy headshell and additional counterweight. 

Shure M44-7 has extremely high output, conical stylus for this cartridge is discontinued, it's much better to add Jico SAS on this cartridge. But the output is just too high!   

It is my understanding is the effective mass for the SL--1200G tonearm is 12g with headshell included.  In addition, these calculators that are available online are strictly approximations at best. It is always best to measure the tonearm/cartridge resonance using proven methods.

Definitely with stock Technics headshell, i agree

And it is much better to use actual Test Record to measure (and to see) resonance than any online calculator which can give you the idea, but not exactly precise measurements.  

Hey, you can use nearly ALL moving magnet and moving iron cartridges on this Technics tonearm, what’s the problem, will you ask for every cartridge ? Don’t use low compliance MC and do not use extremely high compliance MM/MI. Medium or Medium High compliance is what you need. Technics stock shell is light weight, with lower compliance you need a headshell of higher mass and probably Technics subweight for the other side of the arm. Read this and make sure you know your cartridge compliance at 10Hz, not at 100Hz, to make the calculation. Mid compliance MC can be good too. For such expensive turntable you might need something special, not those Nagaoka cartridges, but something much better!