This comparison is not a typical competition between Apple and Droid, but a Droid verses Droid battle. The HTC Sensations biggest competitor is the Galaxy S II.
When it comes to Hardware the Sensation is at a slight disadvantage. Galaxy S II pairs its 1.2GHz dual-core with 1GB of RAM, the HTC Sensation uses just 768MB. The Galaxy device has 16GB of memory packed in, while HTC makes due with just 1GB. There’s an 8GB microSD card in there, but you can add a bunch more memory to the GSII the same way if you want. So that is one win for the Galaxy with more room for storage. Relying on external storage makes the HTC run slower than the Galaxy.