This is my first attempt at an infographic (as it were). So bear with me a little bit, but I think it turned out well.
As you can see, these apps match up pretty well against one another with the only major notes going to Evernote's lack of QR scanning for notes and the absence of rich text formatting via the Catch and Springpad apps. Depending on how you plan to take notes, either of those items could become important to you, but for the majority of users, these apps are all even.
Evernote: For me, Evernote paced this group with the quality feel of the app. The crisp and flexible UI, and sharp colors (mostly green) were appealing every time I opened the app.
Catch: The app and sync settings were king of the hill for Catch. That might not seem like a lot, since it's about app taking, but behind-the-scenes features often make the best experiences.
Springpad: The customizable widget offered by Springpad is sweet. You can set up the widget to make the app perfectly functional for you.
So how do you choose?
The feel of each app is quite different, and I didn't share that in the graphic as it really isn't a tangible thing. The best advice I can give you is to download all three. Take some notes, organize them, refer back to them, repeat that for a week or so and go with the one that is most intuitive to you.
I had been using Evernote for more than a year prior to starting these reviews. So while I tried to be unbiased in my reviews, I also didn't find any compelling reasons to switch. I will say that if I was starting from scratch, Springpad is hard to ignore, I use my widget all the time with Evernote and Springpad's is great.
Download the apps from the Market links below and try them out for yourself:
Let me know if these reviews help you to choose an app or ways that I could make them more useful. I'll probably be staying away from apps that I'm not already using for a while. I worked hard to use Catch and Springpad enough to write a solid review, but feel that I can be much more thorough if I take my time.