i'll post pics maybe when my work schedule settles down...i'm a self confessed tire freak and often change tires for each ride depending on where. these are opinions of course, everyone's tire preference depends on their terrain and riding style. i'll stick with 29er offerings for this post.
kenda nevegal 29 2.2: better than the 26er version, but heavy, slow, and good at everything great at nothing. good choice for your all-round bike that may see a variety of conditions or for a bike trip where you are unsure of trail surface. good front or rear, run backwards in the rear. can run very low pressures. tubeless=easy
maxxis ignitor 29 2.1: fast for a grippy tire, fantastic dry conditions rear tire with consistent braking response, packs up immediately in the wet. not my favorite front tire, especially in loose...but acceptable for a fast setup and makes a great XC race tire. wears very well and maintains grip right to the bitter end. prefers higher pressures. tubeless=frustrating
maxxis crossmark 29 2.1: so fast, so light, shocking climbing grip...not a bad front tire if you are a highly skilled rider and need to go really, really fast in the climbs. wears average...but low profile tread means low lifetimes. great multi-conditions tire for pavement/gravel/dirt machines if you can afford to replace often. stay dry with this one! tubeless=frustrating
WTB stout 29 2.3: simply my second favorite front tire ever (behind the venerable maxxis minion) strong consistent cornering in hard to loose and wet to dry conditions, predictable braking, and unparalleled mud clearing. loves quick corners in rocky terrain, and highly predictable on wet roots. excellent traction in the rear but heavy (1kg) so i don't bother...prefers low pressures. wears average. tubeless=easy
IRC Fire XC 29 2.1: one of the best 26" tires ever (panaracer fire XC) makes an even better 29er tire...stunning grip as a rear tire with acceptable front tire performance. really good braking response and great in loose conditions...although it doesn't clear mud that well. wears terribly, often the knobs rip off before the tire is worn. prefers higher pressures. tubeless=best ever
WTB kodiak 29 2.5: a truly massive tire at 29x2.5, grips like mad both front and rear. hardcore setups only...this beast is well over 1kg per tire. good in the wet and dry, hard to loose with stunning cornering. prefers low pressures. only a true beast will be able to move this as a rear tire. wears ok despite the soft rubber. tubeless=frustrating
maxxis ardent 29 2.4: the most amazing volume/weight ratio i've ever experienced...loves extremely low pressures...great all conditions grip in the front, with highly predictable cornering and braking. doesn't clear mud great, but functions fantastically on wet roots and rocks. surprisingly terrible as a rear tire, great descending/braking but awful climbing traction. wears very well. tubeless=easy
continental MTN king 29 2.4: one of my favorite rear tires ever for all conditions, very light with a high volume casing. prefers higher pressure. clears extremely well and adapts to all trail surfaces well, loves standup climbing (i think due to the really soft lugs). dangerous front tire, with unpredictable folding of the corner lugs when pushed too hard. wears terribly fast. tubeless=easy
panaracer rampage 29 2.3: like the nevegal...but faster and lighter. highly predictable, and good everywhere...but not great anywhere. works front or rear, simply flip the direction. can take pretty low pressure and wears reasonably well. doesn't clear mud well, but good enough to make it a nice all-rounder that i prefer to the nevegal for an unknown conditions tire. tubeless=easy
WTB nanoraptor 29 2.1: at 2.1, the narrow offering in the bunch. simply the best multi surface tire ever produced in my opinion, great for monstercross/gravel grinder/commuter rides. as a rear tire, can make a great fast XC choice for a true MTB. not recommended for wet trails although it handles wet roads great. wears like iron! i built an entire bike around this tire. tubeless=?
WTB exiwolf 29 2.3: heavy but fast tire, works great front or rear but don't lean it over...a lack of real side knobs leaves this one for high grip, dry trails (like slickrock). likes low pressure, and might be impossible to pinch flat. wears like iron. tubeless=frustrating
WTB weirwolf 29 2.5: fast for a seriously high volume tire, fantastic on dry, smoother hardpack but loses grip quickly on loose or wet, front and rear, climbing and braking. likes very low pressure. wears quickly due to the low profile knobs. tubeless=easy
WTB prowler 29 2.1: common as an OEM tire. cheap to buy, with average performance but consistent in all conditions. wears well and corners better than most entry level tires. good fast dry conditions tire and ok as a front or rear. likes high pressure. tubeless=easy
maxxis minion 26 2.5: ok, it's a 26er...but if you are riding hard AM, FR, or DH and you aren't riding a minion...well then you aren't riding to your potential! the best all conditions front tire ever made, i've used this thing on every trail surface in North America and it's always perfect. just had to plug it. likes higher pressure. a great rear tire for descending...too heavy to make a good climber.