This is something a lot of folks have asked about, so I thought I'd answer this question directly with my personal opinion:
After Effects is much better than Motion. It's a lot more powerful and is considered to be the industry standard in motion graphics.
It also costs a lot more and isn't as compatible with Final Cut Pro as Motion is.
Am I switching to After Effects from Motion? No, I'm not.
Motion is excellent for my needs, so it's my tool of choice for motion graphics. I don't need all the features of After Effects, and I don't want to pay the higher price.
But there's more to this comparison
Top 9 Best Motion Graphics Software
Adobe Photoshop - For video groups/transitions creation.
Adobe Illustrator - The industry-standard vector graphics software.
Maya - Intermediate 3D motion graphics software.
Nuke - For creating professional pixel-perfect visual effects.
Blender - Free open-source 2D/3D creation suite.
Top 9 Best Motion Graphics Software
Adobe After Effects - The best motion graphics and animation software
Cinema 4D - Choice of designers and local studios
Adobe Premiere Pro - For professional video and sound co-editing
Mocha Pro - Robust planar tracking tool for VFX and post-production
Adobe Photoshop - For video groups/transitions creation
Adobe Illustrator - The industry-standard vector graphics software
Maya - Intermediate 3D motion graphics software
Nuke - For creating professional pixel-perfect visual effects
Blender - Free open-source 2D/3D creation suite
The cycle of creating a moving animation involves several production processes - from simply drawing a sketch to combining three-dimensional models in a complex dynamic scene. Because of the capacity of some intermediate processes (sometimes they aren’t the required ones, for instance, a video clip may not contain visual special effects), a special motion graphic program is responsible for each separate or several processes, so their complex use is suitable for difficult tasks.