I highly recommend using Amazon's Elastic MapReduce service, especially if you already have an AWS/EC2 account. The reasons are:
- EMR comes with a working Hadoop/HBase cluster "out of the box" - you don't need to tune anything to get Hadoop/HBase working. It Just Works(TM).
- Amazon EC2's networking is quite different from what you are likely used to. It has, AFAIK, a 1-to-1 NAT where the node sees its own private IP address, but it connects to the outside world on a public IP. When you are manually building a cluster, this causes problems - even using software like Apache Whirr or BigTop specifically for EC2.
- An AMI alone is not likely to help you get a Hadoop or HBase cluster up and running - if you want to run a Hadoop/HBase cluster, you will likely have to spend time tweaking the networking settings etc.