There are five types of Concealed Carry Holsters each with it's own combinations of advantages and disadvantages such as comfort, safety, concealment (print) and access.  Concealed Carry Holster manufacturers that you may want to consider include:

Remember that Horsehide more durable than cowhide and will not collapse, a good belt is essential and if you sit all day that you should consider your comfort and concealabilty.  

Compression Shirt Concealed Carry Holsters (Difficult to access  excellent concealment and retension risk for brachial artery)

ABetterHolster.com Compression Shirt Holster

Kramer Leather confidant

I normally don't recommend a Belly Bands due to poor quality but the best of the breed Underwraps Belly Band by Galco

Inside the Waistband Holsters (Easy Access, average concealment most popular concealed carry holster least comfortable or safe when carried sitting and in the appendix position for femoral artery)

Royal Guard by Galco

IWB3 by Kramer this has a forward FBI slant which makes it excellent for sitting

Smart Carry  Not actually an IWB entirely different and ultra concealment

Cross Breed Quick Clip

JS Holster

HBE

Galco SkyOps (not recommended because of extreme tendency to collapse leaving you unable to reholster)

Please also consider tuckable holsters as type of IWB if you dress formally

Pocket  Holsters (Excellent concealment safety comfort Difficult to access sitting safety issues are similar to the IWB for femoral artery)

Galco Pocket Protector

K&B Holsters

High Noon

Ankle Holsters (Difficult to access in a confrontation Comfort average if properly work torture if improperly worn)

Ankle Glove by Galco

Small of the Back Holsters (More Difficult to access than IWB and may have a safety risk for spine injury)

Active Body

Galco SOB

Shoulder Holsters (Concealed until the jacket comes off Safety is similar to compression shirts)

Galco Miami Classic