After The Antipope's excellent posts on the best units in the Ork Codex, I thought I'd do something similar. I'm going to look at what I think are some of the best units in the book, what I think are some of the worst and what I think are some of the funniest. Obviously most of the good units have already been mentioned and I don't really want to repeat what other people have to say.
Burna Boyz - Orks are rubbish at shooting. Moving onto Orks from Space Marines this came as quite a shock to me. However, here we have a unit that auto hits. Plus if you stick a squad in a Battlewagon, they can all fire out as it's Open Topped. Up to 15 flamer templates. Now that can be a lot of hits. Even Terminators are going to start failing some armour saves eventually. They can also use their Burnaz as Power Weapons but not in the same turn that you use flamers. The plan here is simple then, lots of fiery death on one turn and then out of the Battlewagon to Furious Charge with your Power Weapons the next turn (or just keep on flamin') So here we have a unit that is dangerous in two phases of the game which is a rarity in the Ork Codex.
Deffkoptas - These start getting very pricey very quickly as you start adding upgrades. However, with a Scout move and Jetbike movement you should be getting first turn charges with these guys. If you get first turn that means Buzzsaws against stationary vehicles. If you don't get first turn your enemy still has to deal with these guys as they'll be getting Twin-Linked S8 shots on side armour. Don't forget that anything shooting at a Deffkopta isn't shooting at a Battlewagon.
Warbuggies - These guys perform a similar role to the 'koptas but are cheaper. Obviously, they can't fly but they are quick enough to get shots against side armour and they are a plentiful supply of more cheap Twin-Linked Rokkits and that's always good in an Ork army.
Flash Gitz - I love pirates and these guys have a special pirate Ork character but I think that they are the probably the worst unit in the whole codex. The main problem is the price (25 points per model) and the range (just 24") If you're going to take a shooty element to your Orks surely you're going to take Lootas. Yes, they have the stats of a Nob but there are so many other things in the book that can do the same job as Flash Gitz for cheaper.
Tankbustas - 15 points gets you a Rokkit Launcha (S8 AP3), Tankbusta Bombs (6+2D6 armour penetration) and the option for two Boyz to have a S10 close combat weapon that strikes at Initiative for free. Wow, these guys sound pretty good. Then we get to that special rule - 'Glory Hogs' Basically, they always have to shoot and/or assault a vehicle if there is one in line of sight. Even if it's something that they have no real hope of damaging such as a Land Raider. Even if it is out of range. This means ignoring the Space Marines that are about to charge you. This means not charging that enemy squad that is camping on an Objective in the last turn. ah, they coulda been a contender.
Shokk Attack Gun - Now, this is a fun weapon. Unless you have weighted dice, you're not going to take this in a tournament but in a regular game you can definitely have some laughs with it. Not only is the concept of warp-crazed Snotlings funny anyway, some of the guns effects are brilliant. From killing the Big Mek to removing from play anything under the large blast template.
Old Zogwort - Weirdboyz are pretty funny to start with but here's the daddy of them all. Again, you could never really take him in a serious game but have the opportunity to turn an enemy Independent Character into a Squig is potentially awesome. Plus, if you managed to do it to someone like Logan or Calgar it's the sort of story you'd be telling in the bar for weeks. Plus he has all the crazy regular Weirdboy powers as well such as the auto-hitting S10 Melta shot and the bonus Waaagh!
Kaptin Badrukk - Yeah, his unit is rubbish but if Scott Pilgrim has taught us anything, it's that pirates are in this year. Seriously, pirates are cool, even if this guy is no Captain Teague.