To add a bit more depth to your projects, you often want your text to be 3D. In After Effects, you have different options to achieve this and each of them has some advantages. So what option is best for you really depends on your project. Here are the pro's and con's for each of the options.
Creating 3D Text without plugins
If you don't have access to 3rd party plugins, in principle you have two options. If you have After Effects CS6 (or newer versions), you can use the build-in Raytraced 3D feature. It allows to extrude text and other layers to give them some depth. If you have an older version, the best thing you can to is to create many duplicates of your layer and shift each copy a tiny bit more to the back than the previous one. There is also a convenient tool to automate this.
Create 3D Text with Plugins
The following 3rd party plugins also offer easy ways to create 3D text:
- Shape Shifter and Freeform Pro by mettle.com
- Element 3D by videocopilot.net
- Proanimator by zaxwerks.com
Using CINEMA 4D
Another option is to use an external 3D graphics program to render the text. If you have a creative cloud subscription, the obvious choice here is to use CINEMA 4D, since a Lite version of is is already included in After Effects CC. This also has the advantage that you can bring the text from CINEMA into After Effects using the live pipeline based on the CINEWARE effect.
I highly recommend the survey from Rich Young about creating 3D Text in After Effects.