Compared to the cost of the rest of your components, the best thermal paste available is so cheap it isn't really worth considering anything less. You will have cooler computer temperatures with a high quality thermal compound applied correctly. Most important if you want to overclock your cpu and push it to the limit. But heat is the enemy of electronics and having an efficient cooling solution that lowers average temperatures can also extend the lifetime of the machine. Machines are becoming more powerful than the average person needs. Don't underestimate how long your box might live so take the time to do each step right.
Even if you want to use something that is already pre-applied to the cpu fan of your choice, your chip will probably have dust on it from packaging and shipping. So get a cpu cleaner and use it for maximum bond between the thermal compound and the heatsink.