Warrior is a fun Job but can be overlooked from previous MMO's in my opinion. This is the first real tank that i have run since i stopped playing Pally on WoW back when level cap was like 60. But in my opinion, a Warrior is a must have tank for end game. The only downside is their interrupt and their 'enmity' ability when mobs run off. But Warrior is fully capable of keeping 'hate' on multiple mobs. Just keep the mobs in front of you, and use Overpower when needed. You can also target the mob for the DDs to attack and you switch onto the other mobs to ensure you keep enmity on you. If one mob does run off, use "Tomahawk" to get its attention. In all seriousness though, I have not played GLD/PLD long enough to really make the comparrison. I do know that MRD/WAR is fun as hell and can get the job done.
In the beginning levels (1-30) you can solo anything you need, and in Fate grinding, it is definitely quicker and easier to find a party. This is due to the fact that you have to actually be near a mob and you do not have an AoE attack like mages. So get into a party, nobody is going to care that you arent "tanking" the fate mobs. If you are fighting a single mob fate, then Tank it, its fun, and gives good practice at avoiding the little red circle or cones for the mobs powerful attacks. As a warrior you will have the highest HP of the two tanking classes/jobs, and its because you cant heal yourself and dont have a shield, so you will take more damage from bigger attacks, so cross class the "Convalescence" skill from GLD to increase the amount you are healed for. Also, use "Bloodbath" as often as needed. It can save your whole party from wiping in dungeons and can also help win the solo battles for quest lines that are a real pain in the ass.
Levels 31-50 are pretty similar. Only difference in 'Defiance', learn to use it, love it, and never take it off. The lower damage sucks at first, ill admit it. But it will keep the mobs on you and will help when you learn abilities like "Inner Beast" which will heal you for 300% of the damage you inflict with it. Right now i average about 950 a heal. Which certainly helps on the HM Primal fights, cause if the healer is even a second late on a heal, its game over. But this way, you can live and let the healer catch up.
As far as gear goes, 1-20, just buy or craft the gear that is MRD/GLD specific every 5 levels. its the best gear made for tanking. Once you hit 20 start looking at the GC Gear, it actually has some very nice pieces of gear in there. I would usually switch between that and the job specific gear depending on which one provided the most defense boost. To be honest, i am level 50 now with all AF and some DL armor, and i still have never equipped a piece of materia, so i wouldnt worry too much about it right now. End game down the road cool, but i dont have the patience to level the class needed for equipping it.
Foods, i mainly used the Mithkabobs that you can find pretty cheap in Camp Drybone i think. I also liked to use Eft Steak when i could find em/afford them.
Finally, stat allocation. Honestly, i threw everything into STR until i hit level 50, then went back and re-allocated 15 to STR and 15 to VIT. This is cause the gear while leveling is very VIT intensive, and STR isnt bad, but WAR gain enmity mainly through damage. So more damage = more enmity, maybe it doesnt make sense but it worked for me.
I have DL belt, and full AF gear with Ifrit Battleaxe currently and i have been able to tank HM Primals and run Wonderers Palace and Amdapor Keep no problem. Honestly, without a good party, the tank is just a dummy for mobs to practice on, so you can be full DL gear and still get your ass kicked. My point, enjoy what class/job you are playing and make a plan with your party. and then execute how you planned it. The tank and the healer can single handedly cause wipes in dungeons. Try not to be that guy/girl, enjoy your class, and have fun playing it .... it is a game afterall.
I hope this helps someone else. I am bored at work and just want to play, but i cant, so here i am.