Re: San Fran?
I have the Orange San Francisco and it is incredibly easy to unlock, flash and root which is good as the Orange branded default ROM is quite lethargic.... I'm currently running Android 2.2 but there are also stable 2.3 ROMS out there that I might upgrade to at some point.
For the price I'd say that the SF going to be incredibly hard to beat unless you *really* want a dedicated music/video player. The main advantage of the Archos seems to be the CPU which is considerably faster than the 600MHz one in the SF (although this can be over-clocked to some degree and seems perfectly fast enough to me anyway). Another downside could be the battery life which isn't brilliant especially when using a WiFi connection, although if I was just playing music I'd turn any data connections off.
I think you can get the SF for around £95 from Orange now (+10% extra discount for NHS workers and other selected groups) so it's pretty good value although the screen is now TFT-LCD rather than the original AMOLED (although it's still capacitive rather than resistive of course) and provides 480x800 resolution which is twice that of the Archos as is the memory (512mb Vs, 256mb). It can also take 32gb Micro SD cards so considerable room for expansion if you have a reasonably large music collection...
I personally think the Archos is pretty good value but doesn't really come close to the SF as a general purpose device (perhaps because it's not) especially when you consider the screen resolution and expandability. There's also a pretty well established development community for the SF which is always a good thing. Not sure if the Archos has GPS either... I'm guessing it doesn't.
Of course, you can also make phone calls on the SF which can be rather useful if you only want to carry one device around with you :) I spend £10 a month on giffgaff goody-bags which is roughly a quarter of what many of my friends are paying for their 18-month iPhone/HTC Desire contracts....
Yep, I love my San Fransisco :)