might be interesting to note which of these supports the full 1500 mtu (using RFC4638).
I've just got this working on a BT homehub 5 with LEDE and a direct vdsl connection.
I found that the ECI modem I was using was (permenently) limited to 1500 bytes on ethernet, and so mtu=1500 could never be achieved with this in the way as the ethernet must support 1508. (the HH5 also was limited to 1500 until I patched the ethernet driver, but the vdsl driver is already patched).
(mtu of 1500 is really quite important if you run any kind of service behind the router, because MTU discovery on the general internet has some issues. If you are mainly focused on outgoing, then it's less of an issue, but still a nice-to-have if your ISP supports if. BT Openreach FTTC lines are said to support it throughout the UK).
s