Some of what I'm about to say you surely already know, but it's there for the sake of comparison. - For raiding purposes, Warrior defensive disc is irreplaceable. In the group game, that defensive disc is just as godly. That said, there's a general belief (not held by everyone) that knights are just better tanks in the group game. In terms of raw ability to take a hit, warriors are better, but they offer basically no other utility.
Paladin heals are pretty significant throughout EQ and the ability to stun mobs to reduce incoming damage (or buy time for a heal) is nice, and stun aggro on a single target is really high. They can also root mobs off which shouldn't be ignored. (Plus by that point they get a 90% rez). And of course their undead specific stuff. - If they chain stuns, they take less total damage on a single target than a warrior... Assuming, of course, they can stun the mob. Shiftie use to do really crazy impressive solo kills with paladin.
Shadowknights can stack dots and spears for more damage, but lifetaps are what makes them shine for tanking purposes. They can continue to damage while healing themselves. SK's are widely considered better AoE aggro generators, but I'm honestly not sure how good they are at it in that specific era (not that you'll want to have tons of mobs on you at once). They can also snare and feign. This allows them to safely tag mobs from the pack if you're having issues with a pull on bard. Plus their pets can be used either as a really long duration dot, or as a pulling tool. Generally they can survive just long enough for you to get distance between the mobs you want split. SK's 1.5/2.0 is really powerful in the years to come after OoW
That was a very long winded way to say.... Yes and no. All 3 of the traditional tank classes are sufficient tanks, so in terms of straight ability to do their job, no.. It doesn't matter. How you want to achieve that is where picking a specific class will matter. Shadowknights are my personal favorite tank, but you may find warriors 'set it and forget it' style much more appealing. Or love the idea of a clutch heal at just the right moment from a paladin. Given the botting nature of these forums, I'm guessing you won't be playing them all by hand, which makes how many buttons they need to press less of a factor. To that I would say, SK's utility is more straightforward, Paladins can be much more situational, Warriors ... Stand there and look good doing it (warriors do have nuances, but in this era while 3 boxing non-aggro intense boxes, they basically won't matter to you).