N5 Under Illefarnand N4 Treasure Huntprobably got the most use out of me, as I reused and reskinned each multiple times, sometimes for the same group but with a different campaign. The Savage Frontier was fun as a setting book and I don't recall ever reading Swords of the Iron Legion. I may have to correct that. I3 through I5 contain some fun gaming if you can get the party to a desert area.
Shadowdale, Tantras and Waterdeep are mostly forgettable, as they deal with the Time of Troubles (the switch from 1e to 2e) in a very railroadie way. Players actions and achievements meant little if anything as the worlds events happened no matter what. Still, interesting to read to see the mindset going on with the change to 2e at the time.
The Minotaur for Old-School Essentials
*Requirements:* Minimum STR 9, Minimum CON 9
*Prime Requisite:* STR and CON
*Hit Dice:* 1d10
*Maximum Level:* 8
*Armor:* Leather, including shield...