1) There is no such thing as the 'best' interface. You need to consider what your needs are going to be and then find a unit which will meet those needs. For example, how many mics will you want to record simultaneously? If you need more the two, you will have to look at different interface than if you only need one mic (e.g. the ones you mention only have two pre-amps while the Alesis IO|14 or IO|26 have 4 and 8 respectively). If you intend to use a dynamic mic (e.g. the SM57) for quieter signals, then the pre-amps on most (if not, all) $300 interfaces will not do well. Do you need ADAT? What about turntable jacks? Do you want to use Firewire, USB or PCI? and so on.

2) The pre-amps on the Firebox are far from 'junk'. Many people get excellent recordings from it. Assuming that you have a suitable computer and an appropriate TI firewire card and that the card's features match your needs, you could do much worse than buying a Firebox.

3) The sound quality of most $300 units is going to be generally similar. You need to move into a higher price bracket before you will find a big difference.

I'll be using MAYBE an MXL v63m... Firewire is preferred, I will just be recording vocals and guitar.

Agree with hummel.

Another one worth to look at:

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