Agree Focusrite is a little beauty. However I had to upgrade a while back when I discovered that it wasn't delivering enough phantom power to my mic and I needed an interface with its own power supply. (The problem is unique to my mic, not Focusrite.) I bought a second hand UAD Apollo Twin and I have to say it has rocked my world. Here's why:

1. Audio digital conversion blah blah is angelic (like the Focusrite)
2. Great bundle of UAD plugins, including Softube guitar and bass amps
3. Effectively 0 latency due to the unit itself driving UAD plugins, not the DAW (means I can turn software monitoring off altogether when recording)
4. Unison technology. This one is hard to explain but is the best feature. It means enabled plugins respond very much like hardware equivalents through impedance matching etc. I'm no tech head but a Unison guitar amp really feels like a guitar amp now. There's no way I'm imagining this.
5. It comes with a Unison enabled valve mic pre amp plugin that has given my mid priced accurate but unexciting condensor mic mojo to burn.
6. Console software makes it easy to save my favourite setups for recording. I can also route things for proper head phone mixes etc.

It is a bit more expensive than the Focusrite but the older model (which I have) is still being sold.