I watched TNG first and going back to the 60s was… something. Luckily I am a huge fan of Twilight Zone and season 1 of TOS is like Twilight Zone in space.
Spock vs Bones is also a great dynamic in any TV show. There’s some garbage episodes though. But that’s the case for the first few seasons of all the Star Trek.
Might be best to find a “Greatest Hits” list and jump around to see if you like it first. The best episodes (Balance of Terror, the Doomsday Machine) of TOS are as good as the best in any series in my opinion.