If you want to begin recording, you'll need microphone preamplifiers. Direct effects units will only take you so far--you'll eventually want to mic up a real guitar cabinet. You have a need for a headphone amplifier so that you don't accidentally blow your ears away when the software volume control suddenly ramps up, and also because it will drive the headphones more efficiently.
So, 0404 USB.

Also, there is no Firewire port on the version 2 1212Ms. It has been replaced with an EDI port that allows you to attach a MicroDock if you wish to upgrade it to a 1616/1616M.
I own the 1212M and plan on buying the 0404 USB just to fill in some missing features. Plus, it's portable and can be used with a laptop. It can also act as an external DAC/amp away from a computer.
Regarding sound quality differences, the edge in pedigree goes to the Cirrus CS4398 DACs in the 1212M, but the AKM AK4396 is no slouch either. Some people say that the AK4396 is "more musical" while the CS4398 has more detail and resolution. When I first heard the 1212M, I couldn't believe the sheer amount of stuff I was hearing--it really highlights the upper midrange through the extended treble, while still remaining solid in the other ranges. From what I can gather through others' opinions, the 0404 USB is somewhat more laid-back in its presentation, and some might perceive it as being less analytical than the 1212M.