Our Review:

If PicSay Photo Editor is for on the go and Pixlr-o-matic is for home, then Photo Lab Picture Editor is for fun. With over 500 effects, montages and filters, it is definitely something you can use with friends.

With lots of sharing options, this is a fun and social photo editor app. Unfortunately, the free version applies a watermark to the photo, which can be noticed easily. These can be removed one by one, making it a painful process. Every time you remove the watermark however, a dialog opens up asking you to buy the full version.

Apart from this, the application had the slowest photo processor. Here is an image processing speed guide:

PicSay: 0.48 secs
Pixlr-o-matic: 1.60 secs
Photo Lab: 24.40 secs (+12.00 secs to remove watermark)

If you are looking for fun, casual photos when you have plenty of time, I would suggest Photo Lab. If you are looking for something a bit more personalized, I would recommend one of the other two abovementioned.