My top three are:
@Czarcasm (99)
@Little_Nemo (81)
@kayaker (72)
I
@purplehorseshoe
@FairyChatMom
@nelliebly
Within a tight dozen to each other, each well over 200+ replies. In exceedingly fine company, I’d say.
My top one is @Johnny_L.A, which is not who I was expecting. Interesting data there.
@Snowboarder_Bo
@Rick_Kitchen
@WordMan
Wish WordMan would come back.
Yeah, my top three were pretty unexpected, too.
Someone likes to fight! 
Right? My next three are @octopus, @DemonTree, and @Kearsen1.
Wow! You are a sucker for punishment.
I’ll just keep replying to you in a peaceful manner.
magellan01
Bricker
pink_kitten
John_Mace
Sam_Stone
Shodan
Another master debater, I see.
The outlier, pink_kitten, was all from a single thread back in my early days when I participated in fun and frivolous threads in MPSIMS. Oh, I miss those more innocent days. 
Mine are:
@racepug
@pulykamell
@Treppenwitz
@WordMan
The latter three are no surprises, as I’m often in threads about music with them (and I also wish that @WordMan would come back), but @racepug is surprising. I really don’t remember much about them, but I have a hunch that we talked a lot in football(soccer) threads.
Thirded.
For me, it was:
@Johnny_L.A
@Chronos
@silenus
@Chefguy
@Acsenray
It makes sense when I look at it, but I’m not entirely sure I would’ve picked out more than one or two of my top five confidently. We basically got topics of food for number 1, 3, and 4. For 2 & 5, I’m not entirely sure. I guess must be a mix of Factual Questions and food topics. I’m actually surprised @WordMan wasn’t on the list or any of the usual music suspects.
Me too, surprisingly. Eve and Sampiro following.
That’s three people so far with Johnny_L.A at the top! Wow.
@Elendil_s_Heir 571 Various, but lots of D&D
@glee 479 lots of D&D & Chess
@silenus 440 Beer, Pratchett and Heinlein but lots of stuff
@RickJay 412 Mostly Baseball
@CatInASuit 343 lots of D&D
@Marley23 276 Miscellaneous