Blender has no specialty, but I find it to be particularly good at concept sculpting, retopology, subdivision surface modeling, UV mapping, and animation. Zbrush is better at sculpting, but not by as much as you might initially think. The big thing that Zbrush has going for it is that its performance is much more consistent than Blender's multires modifier (the performance of which depends heavily on the initial mesh; on my machine it works best with a base mesh of 8000 polygons). Zbrush works smoothly on my machine with around 6 million polygons while Blender starts to really choke at around the 1.2 million mark with no multires and no dynamic topology. However, the tools themselves are good in Blender and the presence of snapping tools makes it ideal for any sort of modeling that requires more precision than you can get in Zbrush.
I particularly like retopologizing in Blender because you can get results pretty quickly with the shrinkwrap modifier (usually I set it to projection mode and check Negative and Positive) and face snapping. If you are dealing with topology that's mirrored and you have trouble with the shrinkwrap putting verts off of the mirror seam, you can make a copy of the shrinkwrap modifier, apply one of them, go back into edit mode, select all the verts near the mirror seam, make sure Clipping is on in the mirror modifier, and move the verts back and forth along the mirror axis so that they clip into each other. Repeat as necessary. It's the only really annoying thing about retopo in Blender. Other than that Blender is my favorite way to retopo because of its comprehensive modeling tools.
If your character is going to be used in film in a high-end offline renderer you are probably going to want to make use of Mari. No other program can handle as high resolution textures as well as Mari can, but Cycles doesn't handle multi-tile textures like Mari puts out very gracefully so if you need huge textures for offline rendering you would need a Vray or Renderman license. (Both have Blender integration, although the Maya integration is a little more robust for Renderman.) Mari is also hands-down the best application for projecting photosourced textures onto models. For game art 3D-Coat is a very good option although it's strongest when paired with a 2d bitmap editor like Krita, Photoshop, or Clip Studio Paint.
For game art you should also look at Marmoset Toolbag 2, IPackThat, and Knald. Knald has a pretty nice GPU-accelerated baker that's good for quickly iterating on normal maps. If you decide you'd rather not use Knald, xNormal also gives high quality results and is free. IPackThat is a UV packing application that maximizes the usage of your UV space and packs better than most highly trained humans. Saves time and sanity, highly recommended and definitely worth the price even though it sounds like it's not. Toolbag 2 is a real-time renderer that's got good shaders for characters: a really nice skin shader, and anisotropic specularity that's useful for hair, as well as your run-of-the-mill PBR shaders. When you re-export a mesh or a texture Toolbag will automatically reload it when you switch back to it, making it really fast to see the changes to the mesh or texture and drastically reducing iteration time. I would also suggest using a dedicated game engine like UE4 or Unity if you are making an entire game as they're better suited to that purpose than the Blender Game Engine currently.
Basically, you'll be able to reach maximum speed if you use Blender for all of the stuff that it makes fast and the specialized tools where they get the job done particularly faster or better than Blender. Occasionally it might be a good idea to write a Blender Python script to get something done faster, but in many cases once you've got lots of practice and understanding Blender is one of the fastest programs to get many parts of the production done, even some parts for which there are dedicated tools (e.g. Topogun, Headus UV Layout).
Software mentioned in this answer:
Zbrush, $795 USD
V-Ray, $350 per node
Renderman, $495 per node
Krita, free software
Photoshop, $10/month subscription
Clip Studio Paint Pro, $50 (occasionally on sale for $15)
Marmoset Toolbag 2, $129
Knald, $100 or $200
And, last but not least, Blender, free software.