What TIM is best at heat transfer is not the same as what TIM will give us a good seat without any problems .. and getting a good TIM seat is more important than the heat transfer ability of a specific TIM. A poor seat can result in temps 5-10c higher than they should be .. and the top 50 TIMs (except liquid metal) are all within about 3c of each other in heat transfer ability.
Cryorig CP7, Thermalright TF6 or TF8, Noctua NT-H1, Gelid GC Extreme, Prolimatech, be quiet! DC1, or any other top tier company TIM does the job just fine.
If you want to worry about a few degrees difference, worry about the air temp going into your cooler, because many (most) builds have air 5-15c warmer than room going into their coolers after a few minutes of gaming or similar high load application.