Ramparts - 2 - Trash hits somewhat hard, and there's 2 nasty pulls. No CC required though. Bosses are a complete joke, the easiest of all heroics.
Blood Furnace - 3 - Again the trash hits hard, and there are 4 sets that are painful (1 set if you have a warlock to banish). CC not required, but banish is handy. Bosses are also a joke here, even counting the gauntlet before the second boss as part of his event.
Shattered Halls - 4 - Trash is AE heaven. Bosses are mostly easy except for Kargath who likes to splatter cloth wearers. If you run the instance with no cloth and all ranged dps, it's much easier.
Slave Pens - 1 - Aside from the two pulls near the end with soothsayer (MC) + 2 champions (fear), it's a yawnfest. You can skip the majority of the trash and all the bosses are trivial.
Underbog - 3 - A few hard hitting packs at the start, and a couple really hard hitting giants at the end are the only noteworthy trash pulls. No CC needed. Bosses are easy except for the last one that has somewhat of a luck factor if you don't have extremely high dps. Sometimes adds will spawn like crazy and kill off the rest of the group, sometimes no adds spawn at all.
Steamvaults - 3 - The two bog lords at the very beginning are the only challenging trash. There's some fearing to be dealt with, but if you pull to the right places no one will ever run into more adds. Bosses are only a little more difficult than on non-heroic.
Auchenai Crypts - ? - Never bothered to do it. I hated the non-heroic version, and even if it comes up as the daily I'm sure there are much better ways to get badges.
Mana-Tombs - 7 - Trash sucks; lots of stuns and other aggro dumping tricks make CC actually useful here, which makes me hate the place. Bosses range from trivial (Pandemonius w/ shadow resist) to very annoying (Shaffar). Complete waste of time for badges, except for going there just to kill Pandemonius and leave.
Sethekk Halls - 6 - More annoying trash here, but not quite as bad as MT. CC (shackle) is still kind of useful, and there's a few trash pulls that hit really hard. First boss is easy, last boss is easy if your group can follow simple instructions (which means he's actually quite hard most of the time). Raven boss is moderately difficult, depending on how good the druid is at keeping HoT's on the three birds. Having a druid in the group who can spawn him is the only thing that makes the place remotely worthwhile, even as a daily.
Shadow Labyrinth - ? - Only ever done the first boss, and trash up to that point isn't too bad. First boss didn't seem much harder than on non-heroic. I think the ogre fight is the single worst fight they've ever put in the game, so I doubt I'll ever go past that point. Personally I think they should just nuke all of Auchindoun from orbit and start over.
Mechanar - 3 - Easy trash, except for the gauntlet at the end. Charged fist is a pain without someone to interrupt. CC not needed, though having a warlock might save you a couple minutes total by not having to go right at all. Bosses are trivial except for Nethermancer.
Botanica - 4 - Mostly simple trash, but there's a lot of it. No CC needed at all. Bosses are barely harder than on non-heroic, but the demon can still be brutal depending on group make up. Warp Splinter requires high dps if you want to use the easy strat and just burn him down.
Arcatraz - ? - Sounds fairly difficult, but I've never had time to do it when it's come up as the daily, and don't really have any interest in doing it otherwise.
Old Hillsbrad - 4 - Difficulty of this place is greatly exaggerated on places like wowwiki. The only thing I find annoying is that, unlike in Shattered Halls, hunter mobs here can still use scatter shot on heroic. Everything else is just a long series of 'consecrate and AE like crazy' pulls. The bosses are not hard either.
Black Morass - 5 - I give it a 5 because of the times a rift keeper has spawned behind a portal and refused to move so that I could properly consecrate the other adds, and chaos has ensued. Second and third boss can be somewhat painful depending on the group. It's probably worth mentioning that I've never done BM without a shadow priest for the mana regen.
As far as what's actually worth doing for badges (not counting dailies): SP, UB, Mech, Sh. Halls, Ramparts, and MT (Pandemonius only). I don't think I could stomach doing more than 20 badges worth in a single day so I pretty much never do any of the others unless it's a daily. I also avoid anyplace where CC is actually useful, because the dps I bring are usually the ones who can't CC well or at all (elem shaman, dps warrior, hunter, ret paladin, etc.).
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