The simple interface with customizable functions and different versions of php in a nice package. Its very easy to set up hosts with aliases and create databases.

I've tried similar products, and I feel like setup and launch is clunky compared to MAMP. In just a few steps you can easily have your dev site up on your local machine and that's great.

I've been using MAMP for several several years and have to admit that I switched to another local server application a few years ago that I thought was better. However, now I'm back to using MAMP (MAMP Pro to be exact). They've really improved the user experience and functionality of the app in the latest version. One of the headaches in the past was setting up new virtual hosts. I'd have to manually update multiple system config files, which would take too long and it was easy to mess stuff up. Now I can easily create new virtual hosts directly within MAMP in just a few seconds. It's also easy to configure different development environments for each virtual host. And phpMyAdmin comes with MAMP, which makes it easy to create and modify mySQL databases. The newest version also starts up quickly. Pervious versions and other products take too long to start services.