From the hamburger menu you can pick Users (left column, 3rd item). Then adjust the drop-down at upper left from [Week] to [All time]. Then click the “Replies Posted” heading to sort the entire user roster by that number. You’ll be listed first and highlighted, then everyone else below you in descending order.
All time #1 is Elendil_s_Heir with 135K. Chronos is second with 115K. I’m in 13th place with almost 66K which is not quite half of Elendil_s_Heir’s score.
You can also sort by posts read, topics created, etc. Comparing posts made vs topics started, Czarcasm and Johnny_L.A are two of the very few to be very near the top of both lists. That shows a nice sense of balance. Me, I rarely start topics; only 1 in ~250 of my posts is an OP. For e.g. Czarcasm, 1 in 22 of his are OPs.