Most influential RPG

[Theory of Games]

4e didn't live up to Hasbro's expectations, but compared to any other RPG it was a magnificent success in objective terms. Unless of course you believe Chris Sims, Owen K. C. Stephens, Greg Bilsland, and Trevor Kidd are all lying liars who lie.

4e didn't live up to the expectations of the many of D&D players, which is why Pathfinder temporarily became the #1 selling ttrpg. It is what it is. I read your link:

• Sims denies PF outsold D&D4e and brings up reasons for 4e's failure without citing any real sales numbers
• Owens denies PF outsold D&D4e and literally says no one has access to ttrpg sales numbers outside of the individual ttrpg companies (suggesting ICv2 lied) without citing any real sales numbers
• Bilsland and Schmevor (what a name) both only chirp in to agree with Sims' comments without citing any real sales numbers

Without some evidence here, it's just the opinions of a handful of people vs. ICv2. One thing that helps ICv2 is the Roll20 Orr Report of Q3 2014 which reveals, at least on Roll20, the majority of GMs reported their groups were playing PF1e over ANY (other) edition of D&D.

I'll go with ICv2 and the Orr Report as indicators that PF1e dominated D&D at certain points. I also think it's good for the ttrpg hobby to NOT have one game constantly dominate.

 

[Committed Hero]

It's difficult to determine whether Vampire was a response to the zeitgeist of the period and/or benefited from TSR's decline. But there is no question it belongs in the top 3. If you quibble about editions, include it in the World of Darkness.

I also like to point out that whatever his weaknesses, Gygax did what a lot of game designers don't care to - which was to market his game. His efforts in the 80s laid a lot of the groundwork for D&D's endurance. I think he could have thrived in the social media era, assuming he could refrain from the odious habits of the old guard.