Fritz! has the most mature IPv6 support I've found in any device. I have a 7390 which will happily accept prefix assignments from the ISP, or can enable an IPv6 tunnel for ISPs not yet ready.
My internal systems get IPv6 addresses using SLAAC, including my iPad and iPhone.
"It just works"
Previously I was using a Cisco 877W with IPv6. Terrible; the integrated bridging didn't support IPv6 but had to be enabled for local multicast support (for AirPlay, etc). The end result was that IPv6 only worked for me wired, but not wirelessly.