The Fastest way for Honor Hold & Thrallmar Rep
These two Factions are the two first ones that players encounter after entering the Dark Portal. This is one of the reasons why they are also the easiest Factions in TBC Classic to gain Rep with.
The fastest way to get to Exalted status with Honor Hold and Thrallmar is to do Blood Furnace and Hellfire Ramparts until Honored, without doing any quests in the zone. After that, you have just above 50 Quests, which will give you a total of around ~13k Reputation. With that, you will be Revered already. Then you can run Shattered Halls, either Normal or HC, until you reach Exalted.
In the image below, you can see the Honor Hold and Thrallmar Rep Guide and which things work at what points in your rep grind.
Honor Hold notable reputation rewards
Along with several Leatherworking Patterns, a Jewelcrafting Design for a Tank Trinket and some level 70 blue items, there are also 3 notable epic reputation rewards for reaching Exalted Reputation with the Honor Hold Faction in TBC.
Thrallmar notable reputation rewards
Because Honor Hold is only available as a Faction to the Alliance, Thrallmar, being the Horde equivalent of Honor Hold, has very, very similar Reputation rewards. There are several Patterns and Designs for Professions and three epic items, with almost exactly the same stats as the Honor Hold ones.