Ranked by "easy", "normal", and "hard". This is based on the hardest boss of the instance. Please post your views and I'll update the post as needed. The rating is based on an "average" trinity group. The numbers in paranthesis are the number of emblems for the entire instance.

Easy
- Utgarde Keep: Keep (3) - strategy link
- Drak'Tharon Keep (4) - strategy link
- Gundrak (5)- strategy link
- Caverns of Time: Culling of Stratholme (4/5)- strategy link

Normal
- Ulduar: Halls of Lightning (4)
- Azjol-Nerub: Azjol-Nerub (3) - strategy link
- The Violet Hold (3) - strategy link 1 strategy link 2
- Utgarde Keep: Pinnacle (4) - strategy link
- Nexus: The Nexus (5 - Telestra can be tricky depending on group setup) - strategy link

Hard
- Ulduar: Halls of Stone (4)
- Azjol-Nerub: Old Kingdom (5)
- Nexus: The Oculus (3) - strategy link (not really)

Please supply input/opinions and I'll rearrange as needed.