I've been enjoying jungling with two champions, Amumu and Hecarim, that I used a bit in S3 and S4, but really haven't used much in S5 until recently.

They both share some key characteristics, which are 1) Team fight altering ultimates and 2) They do respectable damage even when they are somewhat behind in items.

I feel like Amumu has slightly better early ganks with Bandage Toss for a gap closer, but Hecarim has an advantage at getting around the map due to a number of factors A) I run movement speed quints on him B) You can pop Warpath after basing to get back into the jungle faster or get cross map faster C) Running Ghost.

Aside from the crowd control and damage they provide, a perhaps overlooked or undervalued aspect of their area of effect ultimates is that they are a clear signs to your team that the team fight is here. ADC or APC slightly out of position? Boom. Here is the fight. Take out the high damage target that misstepped and mop up from there.

Hecarim has as slight edge in getting his ultimate off over Amumu because he can hit it from odd angles and over walls without the precondition of using Bandage Toss or Flash to get into position.

Amumu is a better tank due to the passive of Tantrum and a better tank killer than Hecarim because of the percent health damage he does via Despair. High health targets literally melt if they are standing around Amumu for any length of time especially if you itemize Liandry's Torment.

Amumu is somewhat easier to kite than Hecarim because once Bandage Toss is down he really doesn't have a way of getting to a target, though Turbo Chemtank gives him another movement speed option. Hecarim typicall either runs Black Cleaver or Trinity Force, has his ultimate, Onslaught of Shadows, and Devastating Charge all of which help him get to and stick to targets.

;tldr if they have a bunch of tanks go Amumu. if they have a bunch of squishies or only one dedicated tank than you are likely to get more mileage out of Hecarim.

Hecarim Item Build

For Hecarim the build I've been following is

Skirmisher's Sabre with Enchantment: Cinderhulk
Trinity Force opting for Phage first for the additional tankiness and stickness
I also tend to pick up basic Boots after Phage as movement speed is really good on Hecarim
Frozen Heart - buy Glacial Shroud first if no AD threat has obviously emerged for the cool down reduction
Spirit Visage- I'll swap this and Frozen Heart if they are magic damage heavy
Boots of Swiftness or Mercury's Treads - if they have more than two forms of CC that can stop you in your tracks than I will usually opt for Mercs

Final item judge off how their team is doing. If you are taking a lot of mixed damage than Guardian Angel or Zz'Rot Portal are both decent buys. The passive, Point Runner, from the Raptor Cloak portion of Zz'Rot Portal is nice on Hecarim for the additional movement speed near functioning and fallen turrets.

If the their team is autoattack heavy than Thornmail is a good buy.

Amumu Item Build

With Amumu you can go one of two directions, full tank or damage tank.

The start of the builds are going to be similar

Ranger's Trailblazer with Enchantment: Cinderhulk
Turbo Chemtank
Mercury's Treads or Ninja Tabi
Frozen Heart

At this point the builds deviate

Mohr damages finish with

Abyssal Mask
Liandry's Torment

Mohr tanksiness finish with

Banshee's Veil
Thornmail

You have to judge how the game is going to decide to build full tank or damage tank. If you are behind and you are better off as an engage and peel bot because either your ADC or APC are doing well then go full tank. If the game momentum is in your team's favor then going for more damage will help you end the game faster.

Both champions are fun in their own way. If you like melting faces just by standing around then Amumu is your mummy. If you like to charge in and stick to their back line then Hecarim is a fit pony for carrying you into the fray.

Hecarim - Black Cleaver vs Trinity Force

I've tried both on Hec jungle and I feel like Trinity Force is the better item for him in virtually all cases. Yes TF is 703 more g than tBC, but Hec makes superb use of every stat and passive provided by TF.

At this point the only time I would get tBC over TF is if I was the main tank for the team and somehow got seriously behind (e.g. loading into the game late or getting screwed by a series of invades or ganks with poor outcomes.)