I have been following this thread for quite a while now and I would like to share my own 2 cents, if you all don't mind.
Well, I know that clerics and druids have summoning abilities, but in general the Wizard/Sorcerer spell list has spells of much greater ability. Invisibility? Magic missile? Fire ball? Hard to go wrong with these, and hard to equal them with a cleric, unless you have some type of additional books that seek to make divine casters more powerful.
I would say that you can go very wrong with direct damage spells. Apart from a very narrow window (typically from lv5-8), they are for most part fairly lackluster compared to what your arcane spellcaster could be doing instead. At lower lvs (lv1-4), you lack the caster lv to power damage spells, so you are usually better off with spells whose effects are less dependent on caster lv, such as sleep, benign transposition, grease, colour spray, glitterdust, web and cloud of bewilderment. At the cost of a single spell slot, you can potentially shut down the entire battlefield or at least debuff and weaken the enemies sufficiently for the fighters to step in and finish the job. Much more efficient than hitting a single kobold warrior with magic missile.
Past that sweet spot, enemies' hp typically scale at a much faster rate than your direct damage die, so it is an increasingly uphill task to maintain your effectiveness unless you resort to save-or-die spells, but that too is also much harder to use successfully in 3.5 with the nerfing of spell power, unless you really go out of your way to lower the enemy's saves first (eg: limited wish). But at the end of the day, the amount of resources expended just to make this work may not be any less than just blasting it.
Likewise, enemies all continue to fight as well regardless of whether they are at full hp or at 1hp, so for most part, damaging them won't affect their offensive capabilities one bit. Which is why I feel that it is generally better to just disable them control spells like black tentacles, solid fog, stinking cloud, bands of steel, as well as metamagicked versions of lower lv spells such as sculpted glitterdust/stinking cloud. Summons are better at absorbing damage since you don't have to worry about healing their wounds, and they double as a free source of damage, flanker or aid-another ally.
By reducing their attacking capabilities, you are not only enabling your fighters to finish them off more easily, but also negating their capacity for dealing damage, which translates to an indirect form of healing since your fighters are taking less damage. This is why direct damage tends to be less efficient than battlefield control.
Conversely, divine spellcasters can make for excellent fighters. Clerics can wear heavy armour, use shields and assuming they took the war domain, wield a decent weapon, using buff spells to augment both their fighting capabilities and that of the party. Likewise, the druid can wildshape and use natural spell to cast spells while shapechanged, and past 8th lv, can remain in wildshape practically 24/7, effectively becoming the equivalent of a spellcasting fighter. Wild armour/shield and wildling clasps let you work around the drawback of your gear normally not carrying over in wildshape, or alternatively, have the wizard buff you with long-duration spells like mage armour.
Healing is for most part an inefficent option which should only be carried out in between combats, not during (unless circumstances are really dire), and even then, you can craft/purchase wands of vigor to supplement your healing, freeing up divine slots for more useful spells. Druids can summon in unicorns (acting as a decent support fighter during combat, and a passable healer after combat), and even rogues can UMD healing wands. Thus, it is generally better to focus on taking down your enemies ASAP before healing (because each round you take them down sooner is one less round they can attack, meaning they deal less damage, and so you need to heal less). Likewise, using healing potions during combat is about one of the dumbest moves one can possible make, so I wouldn't view that as a viable alternative either.
If I were a fighter in that party with that jerk of a cleric, I'd say fine and then let the next Ogre through to attack the back lines of the party. If they aren't going to fulfill their party role and be a team player, I see no reason why I should risk my neck for them. After all, that Ogre will be lots easier for ME to down after he's taken some damage, and the cleric will do SOME damage before he's dying, simply because the fighter's not allowing him to spend a few rounds buffing and the rogue's not serving as a scout, which is dangerous, don't you know...
Sadly, my experience is that the outcome tends to be the same regardless of whether the fighter is willing to assume the mantle of party tank. Why? Because unlike the 4e fighter, the 3e fighter utterly stinks at being a tank, because he has no means of instigating the enemy to want to attack him over another PC who would have fewer hp, be less heavily armoured and possess greater potential for mass destruction. There is absolutely nothing he can do to say, convince the dragon to attack him, not when the dragon can just fly overhead to assault the weaker wizard or rogue, and the fighter can do little but just continue attacking the dragon, all while helplessly watching it eviscerate the other PCs. Nor is he an effective battlefield controller, since popular tactics such as grapple or tripping have their own limitations, and monsters tend to be just as good at this, if not better, because of their size/str advantages.
In fact, I have found that a wizard can make for an even better tank than a fighter. My 5th lv focused specialist conjurer could bring in huge fiendish centipedes, which are able to grapple foes with a higher degree of success than any fighter ever can. This allows me to "tank" the selected foe by forcing it to remain where it is and deal with the centipede, even if it does not want to, either removing it from combat for that few rounds, or disabling it while the other PCs finish it off.
My impression of the 3.5 fighter is that its role of more akin to that of a 4e striker. He has the capacity to deal a lot of damage, nothing more. So he should typically hang back and wait for the spellcasters to lock down the entire battlefield (using fogs, walls, summons etc), before wading into combat and finishing off the weakened foes (which in turn helps the spellcasters conserve resources as they now have a ready source of direct damage - the fighter).
Likewise, I do not think it is fair to say that one class is any stronger than the other just because it would win in a PvP fight, since classes were conceptualized based on how much they could contribute in a typical 4-PC party, not how they fare in an arena matchup. The fighter, as with any melee PC, has his place. Unfortunately, it is not always a glorious one, since your role may well be synonymous with that of the druid's animal companion (considering that at lower lvs, a riding dog's stats are roughly equivalent to that of a fighter).
What do you all say?
