Well… if you’re looking for a recommendation, I used GD900 “only” because it was the cheapest on the market at the time. I paid $12 for a 30g tube which was way overkill for my needs. Then some shmuck on YouTube did a test of all thermal grease and this outperformed others and afterwards, it shot up to $30 per 30g tube. Note that his test only showed a 2-3C difference between that and Thermal Grizzly metallic at nearly 50X the cost.
Why mention this, because it’s same grease used by other thermistor suppliers.
Again, the point is, buy the cheapest “Shite” you can find and it will work just fine.