2.35's:
I have run a few combo's that I like and a few that suck. I was a Nevegal fanboi until Kenda released the excavator. I still run a Nevegal on the rear b/c I won't go less than 2.35" and the Nevegal is slightly narrower than Excavator with the same casing label. The 2.35" Excavator rubs just a tad in hard leans and crooked tranny's. So now, I roll on a 2.35" Nev Rear / Excavator front. The Excavator is an amazing tire...predictable, grippy. The Nev will roll a bit faster, but breaks loose sooner. I don't care about rolling resistance (to a point)...IMO the added traction benefit trumps it by far. I did try a 2.5r / 2.8f setup for XC for a bit, but that was a bit over the top and killed me.
2.1's: I have a 1998 Komodo that I'm running rigid. If I could fit a 2.35 in the frame, I totally would...but since I can't, I run a 2.1" Kenda Smallblock 8 rear with a 2.35" Nevegal front. I had 2.1" SB8's on F & R to begin with, and it was super fast...but just blasting a 30-40mph gravel path "felt" a bit sketchy. As soon as I threw the 2.35" Nev up front...I grew some serious confidence in the bike. I pushed so much harder. Added volume lets me run lower pressure for added traction, smoother ride on a rigid which equated to increased confidence allowing me to push harder / more aggressive.
Tread pattern, durometer, casing thickness all have equal bearing on a tire purchase. I don't do straight up DH or FR, so I run a Kevlar bead. If I did the prior, I'd go wire with DH casing.
I tried Conti Mtn Kings when I tried to XC'out my Komodo...I hated them. They actually caused me to hit a tree due to their crappy grip. I've done the uber light Python's, most of the older IRC line, some WTB's...including Raptors. (decent for mud) A couple different Tioga's. I'm still sold on the Excavator for over all traction though. I've never rolled with Maxxis, so I can't comment. I've heard great things though.
I'd like to give the Slant Six and High Roller a shot. Looking at the tread pattern though...I'd most likely only be happy with them as a rear tire with a more aggressive tread up front.