I have been thinking which to use.
I am already using Google App Engine (Java) for a few years, running a couple of web apps on production. And paying them ever since they started charging.
I tried a few apps on Dotcloud, but never yet deployed any on production.
Here’s what I think of them.
+ Reliable + Great Docs + Great Community + On demand scaling - Some restrictions - User Agent has GAE..
+ Shell access + Can use pip install + Can run worker processes - Too much things to handle - Easily use up workers/services - Redis, MySQL, Python, ... - Higher startup cost
As a one-man-show developer, my bet is on GAE.
Though it is less flexible, it will save time and money.