I have multiple favorites. To start off, the 49th Indiana Infantry Regiment, the 7th Tennessee Cavalry (CSA), 3rd Tennessee Mounted Infantry (Union), the 1st Tennessee Infantry (CSA) (Archer's Brigade), the 154th Senior Tennessee Infantry, and the 24th Mississippi Infantry.
49th IN- Direct ancestor, James M. Cummins, mortally wounded at Chickasaw Bayou.
7th TN - Forrest's own regiment he served and armed with himself
3rd TN - Direct ancestory, James J. Voyles, enlisted and survived
1st TN - Veteran regiment that held its own against the Iron Brigade at Gettysburg for a while despite being out numbered / out flanked
154th TN - Veteran, pre-war militia regiment that was raised in my home town. Pre-war militia, a history that made them better trained and equipped than most
24th MS - Direct ancestor, James Long, KIA(?) at Corinth, MS in 1862