Find something that is just a DSL modem/bridge without the frills of
Wireless networking, NAT, etc. I've got a company that is using a
DLink DSL Router/Modem in bridge mode and haven't had a problem with
the modem for at least 2 years. I'm very happy having a DSL modem that
is only smart enough to do the DSL authentication and dump an Ethernet
connection to a better device. Separating the modem from the router
makes life easier if you decide to change to cable in the future. Say
you want to move from 802.11B to 802.11G to 802.11N to
802.11whateverisnext, or change to a router that has external storage,
move to a Time Capsule, whatever. The less you have to involve your
ISP with such a change the better. :)

Once you have a DSL modem, pick a router that is supported by OpenWRT
(www.openwrt.org) and/or DD-WRT (www.dd-wrt.com).

OpenWRT Supported Hardware:
http://wiki.openwrt.org/TableOfHardware?action=show&redirect=toh
DD-WRT Supported Hardware:
http://www.dd-wrt.com/wiki/index.php/Supported_Devices

I go by the OpenWRT list. You want one that says Supported, not WIP or Kamikaze.

Even if you don't use the 3rd party firmware you will still end up
with a Router/AP that is better behaved than most of the devices made
by the same manufacturers but don't run OpenWRT/DD-WRT.

This is all my opinion on how I like to have things setup. I like
having the option of dropping my cable or DSL service without having
to swap out my router/firewall. Good for threatening to cancel your
cable service. :)

-- 
Andrew S. Zbikowski | http://andy.zibnet.us
IT Outhouse Blog Thing | http://www.itouthouse.com