As well as cab type, line length sometimes makes a difference. Generally speaking the Billion 8800NL (R1) and Zyxel VMG8324/8924 appear to perform best on shortish lines. (BCM63168 chipsets).
> Can anyone suggest a router and compare the sync results to any others you have tried?
I'm on an ECI cab. When testing a modem I usually use the HG612 as baseline performance. - You can see how it compares with a VR900
here. From memory the VMG8324 gave me circa 3.8Mb more headline than the VR900 and ~3.5Mb more than the HG612.
For a cheap router the
TD-W9970 with its BCM 63381 modem chipset performed quite well, but that would be a backwards step for you when it comes to wifi. Although Ive not done a write-up, the Zyxel VMG1312-B10D performs almost identically (BCM 63381).
If you are not wanting to take a backwards step on the wifi, then perhaps look at the Zyxel VMG8924-B10A whose modem performance is exactly the same is the VMG8324.