In this guide I will aim to give you an in depth idea of what the Iops can achieve, where they excel, how to build an Iop and the roles that can be used to achieve easy victory for your team in both Dofus (PC) and the Touch (mobile) versions.
Characteristic Points
Intelligence. The Intelligence Iop is a close range single target hitter. Int Iop is something between a Nuker like the Strength one but does his job a bit worse. The best Int Iop is often played in addition to the Agility element with the Class Item that makes Sword of Judgement non LoS.
Strength. Strength is the most powerful element for the Iops. From Sword of Iop which is a ranged attack that hits in an AoE X shape to single target nuking Spells like the Iop's Wrath the Str Iop has it all. Usually Str Iops are often needed for many dungeons, especially their achievements as Iop is the only Class that can do over 6000 damage in a turn EASILY and with teams that are focused on boosting the Iop only the sky is the limit...
Agility. The Agility Iop is relatively strong but can't really compare to the Strength Iop. When paired with Intelligence, the Int/Agi hybrid can become a beast for PvP though.
 Chance. The Chance Iop absolutely sucks. Dofus Touch doesn't have Chance Iops but the PC version does with the new Variants. The Chance Iop needs some serious buffs if he wants to be even 10% of the other builds. Don't play this unless you fancy losing a lot.

Dofus (PC)

Full Strength Iop

The Strength Iop is the most powerful one and it takes zero brain to play one. It can get quite boring but if you want an easy win at everything you do...

Low Level (~60)

This Low level set is solid and quite cheap, if you can't afford overmaged Vitality on the pieces go ahead and put some of your Points into Vitality.

Dazzling Cloak is great because of the AP.

Coral Ring, has kinda bad stats but it's the only thing that fits this set.

Badoul's Mane is important for the MP it gives, if you don't need the MP take something else.

Lucky Dice is BiS for any low level Chance or Strength character.

Sandals Koholiks are the only low level item that gives MP.

Gelano, preferably Vitality overmaged.

Caracap.

Green Turtle Belt.

Sponghield, get one with a lot of Vitality!
The best Trophies for the Low level Strength Iop set: Cawwot Dofus, Minor Survivor, Minor Maniac, Silver Dofus. The best mount is a Seemyool. Kompost can be okay if you have a lot of health.

Mid level (90~110)

This set is very strong but you might have some trouble acquiring the parts, Reedolph Hoves are pretty much non existent on the new servers, you can find an easy replacement though.

Redolph Hooves.

Chouquish Belt.

Royal Pippin Blop Ring.

Gorgoyle Cloak.

Gorgoyle Amulet.

Stalk Sword.

Bwork Chief Helmet.

Sponghield.

Gelano. MP exo is always welcome.
The best Trophies for the Mid level Strength Iop set: Shaker, Nomad, Jackanapes, Rabid, Vigour and Miracle Man. The best mount is a Seemyool or Kompost if you can get a lot of Vitality overmaged on items and a MP Gelano.

High level (160~199)

This is the best set you could possibly get at this level and it will be powerful enough to carry you up until level 190. If you plan on keeping the set for a long time focus on overmaging Vitality on the pieces.

Drhossil Belt.

Mandring.

Moowolf Cloak.

Gelano.

Gorithm Sandals.

Amoolet.

Nekochief.

Inn Shield.

Zoth Warrior Axe.
The best Trophies for the High level Strength Iop set: Shaker, Nomad, Major Rabid, Crimson Dofus, Major Miracle Man, Major Goliath or Major Maniac. The best mount for this set is a Seemyool or Kompost if you can get MP exo on an item.

End game (lvl 200)

This set is mainly focused on getting 12 AP so you can do the Jump Wrath combo, there is a 11 AP variation that uses Catseye Bow to deal a lot of damage, at the cost of no Wrath combo ofcourse.

Professor Xa's Cloak.

Stilted Shovel, you can replace it with a Catseye Bow if you want to do damage from range.

Gein's Hat.

Dark Court Belt.

Bearbaric Band, MP exo prefered.

Captain Amakna Shield, replace with Four-Leaf Shield if you go Catseye Bow.

Treadfast Boots.

Treadfast Amulet.

Hairsh Bracelet, AP exo needed for 12th AP.
The best Trophies for the End game Strength Iop set: Shaker, Nomad, Major Vigour, Major Rabid, Crimson Dofus and Jackanapes. Mount: Karmeleon or Armoured Dragoturkey, you can also try a Seemyool for even more resists!

Dofus Touch

Low Level (~60)

Dazzling Cloak.

Coral Ring, has kinda bad stats but it's the only thing that fits this set, there are other alternatives such as Green Scara Ring.

Badoul's Mane is important for the MP it gives, if you don't need the MP take something else.

Lucky Dice is BiS for any Low level Chance or Strength character.

Sandals Koholiks are the only low level item that gives MP.

Gelano, preferably Summons exo because this set lacks Summons.

Caracap.

Green Turtle Belt.
The best Trophies for the Low level Dofus Touch Strength Iop set: Cawwot Dofus, Minor Survivor, Minor Maniac. The best mount is Crimson and Emerald Dragoturkey.

Mid level (90~110)

Royal Pippin Blop Set has great stats, with the other fillers this custom set is really strong.

Royal Pippin Amublop.
Royal Pippin Boots.
Royal Pippin Belt.
Royal Pippin Blop Ring.
Stalk Sword, can be swapped for Treechnid Root Bow if you want more AP.

Bwork Chief Helmet.

Gorgoyle Cloak.
Gelano, MP exo if you want 5 MP.
The best Trophies for the Mid level Dofus Touch Strength Iop set: Jackanapes, Goliath, Maniac, Survivor and Crimson Dofus. Mount: Emerald and Crimson Dragoturkey.

High level (160~199)

The Moowolf set is most commonly used with Iops that want to go 12/5 without any ultra expensive exos at this level.

Moowolf Boots.

Moowolf Hat.

Moowolf Ring.

Moowolf Belt.

Amoolet.

Moowolf Cloak.

Zoth Warrior Axe.

Gelano, MP exo prefered.
The best Trophies for the High level Dofus Touch Strength Iop set: Jackanapes, Major Goliath, Major Maniac, Major Survivor and Crimson Dofus. Mount: Emerald and Crimson Dragoturkey or Kwyness for 12 AP.