My own PCs I've always self built, much better choice and you can take advantage of the much better hardware warranty, most PC builders only offer one year on hardware, subsequent years are labour only, but a lot of hardware comes with much longer warranties.
I've used all the above mentioned companies, along with many others, this website is an excellent resource for spec-ing a system and checking compatibility.
https://uk.pcpartpicker.com/Just double check prices separately as it does occasionally get it wrong.
I may also have a firewire card you can have, although I suspect it may be PCI and therefore not compatible with recent motherboards, I'll have look if I remember when I get home.