1. Greaves of the 7th Legion (Heroic) > Anub’arak (Heroic) > 437.78 Best in slot
2. Greaves of the 7th Legion > Anub’arak 25 > 375.39
3. Battlelord’s Plate Boots > Blacksmithing > 296.27 Best in slot 10 man only
4. Plated Greaves of Providence > Trial of the Champion (Heroic) > 289.04 Best pre-raid
4. Melencholy Sabatons > Malygos 25 > 287.48
5. Sabatons of Sudden Reprisal > Anub’Rekhan 25 > 264.33
6. Boots of the Underdweller > General Vezax 25 > 247.06 (337.71) Best with hit
7. Death-Inured Sabatons > Knights of the Ebon Blade (Exalted) > 236.7
Pre-raid your best bet is to go for the Plated Greaves of Providence from Trial of the Champion (Heroic). However, since you need revered with Knights of the Ebon Blade anyway for your head enchant, if those are refusing to drop then just keep that tabard on until you can grab a pair of Death-Inured Sabatons to tide you over.
At the moment I’m raiding with Greaves of Iron Intensity from 10 man Iron Council which score 219.77 or 323.37 with hit. I’m using them for hit so I get the second score. They’re basically minature Boots of the Underdweller. I’ve not listed down that far because the best scoring boots these days don’t seem to carry hit. So, instead, stick with your pre-raid boots until you can get some Greaves of the 7th Legion. Given the cost of Battlelord’s Plate Boots I will skip those, since they aren’t best in slot.