I'm currently trying to get the best bang for my buck from a small pool of undead for one of my PCs (restrictions are 10 HD controlled total, no individual more than a CR of 1, all sourcebooks allowed). I've currently got 2 Crocodile Skeletons, and either 1 Skum Zombie, or 2 Wolf Skeletons. Stat blocks below. The PC also has about 1,000gp spare, which means he'd be able to outfit humanoid skeletons with decent gear, and some throwing weapons. It's for an endurance challenge, so the goal is to keep them alive as long as possible, which is why I've been looking primarily at 3 and 4 HD undead with DR of some kind.
Crocodile Skeleton
Medium Undead Hit Dice: 3d12 (19 hp)
Initiative: +6
Speed: 20 ft. (4 squares), swim 30 ft.
Armor Class: 13 (+1 Dex, +2 natural)
Base Attack/Grapple: +1/+5
Attack: Bite +5 melee (1d8+6) or tail slap +5 melee (1d12+6)
Full Attack: Bite +5 melee (1d8+6) or tail slap +5 melee (1d12+6)
Space/Reach: 5 ft./5 ft.
Special Attacks: —
Special Qualities: Damage reduction 5/bludgeoning, darkvision 60 ft., immunity to cold, undead traits
Saves: Fort +1, Ref +3, Will +3
Abilities: Str 19, Dex 14, Con —, Int —, Wis 10, Cha 1
Feats: Improved Initiative
Challenge Rating: 1
Skum Zombie
Medium Undead (Aquatic)
Hit Dice: 4d12+3 (hp 29)
Initiative: +0
Speed: 20 ft. (4 squares), swim 40 ft.
Armor Class: 14 (+4 natural), touch 10, fl at-footed 14
Base Attack/Grapple: +2/+7
Attack: Bite +7 melee (2d6+5)
Full Attack: Bite +7 melee (2d6+5) or claw +7 melee (1d4+5) or slam +7 melee (1d6+5)
Space/Reach: 5 ft./5 ft.
Special Attacks: —
Special Qualities: Single actions only, damage reduction 5/slashing, darkvision 60 ft., undead traits
Saves: Fort +1, Ref +1, Will +4
Abilities: Str 21, Dex 11, Con —, Int —, Wis 10, Cha 1
Feats: Toughness
Challenge Rating: 1
Wolf Skeleton
Medium Undead Hit Dice: 2d12 (13 hp)
Initiative: +7
Speed: 50 ft. (10 squares)
Armor Class: 15 (+3 Dex, +2 natural)
Base Attack/Grapple: +1/+2
Attack: Bite +2 melee (1d6+1)
Full Attack: Bite +2 melee (1d6+1)
Space/Reach: 5 ft./5 ft.
Special Attacks: —
Special Qualities: Damage reduction 5/bludgeoning, darkvision 60 ft., immunity to cold, undead traits
Saves: Fort +0, Ref +3, Will +3
Abilities: Str 13, Dex 17, Con —, Int —, Wis 10, Cha 1
Feats: Improved Initiative
Challenge Rating: 1