Putting in a combined ADSL modem / router (with or without wifi) is really independent of which ISP you choose. You would be able to use the device with whatever ADSL service provider you go with.
Of course if you are switching from ADSL to cable, you might well want a different router.
It is possible that another provider might include a wifi router / firewall with their package, though. Maybe read up the possibilities and offerings before taking the plunge.
SD