Ideally, there should be two stations between Sandhills & Moorfields; one around Lightbody Street and another not far north of Leeds Street. Google maps suggests a station at Lightbody Street would only be an 8 minute walk from Bramley-Moore Dock, as oopposed to 13 minutes for Sandhills. I doubt Merseytravel would be confident getting two considering how long the process is to get such things approved and built in this country. If just one of the two got built, then the other could easily be decades away or never happen, risking sub-optimum station-spacing. If they were to go for just one, then a site around the northern part of Love Lane would be more equidistant between Sandhills and Moorfields; still relatively handy for much of the central docks but about 11 minutes from Bramley-Moore; thus only marginally better than Sandhills.
The ideal solution for Bramley-Moore and the rest of the central docks would be a revived Overhead Railway, in the form of a DLR-type system. The route would be broadly similar to the old one connceting with Brunswick at the south (possibly even Dingle!) and running along the waterfront. I wouldn't run it as far north as the orignal though and would make it interchange with Sandhills, which would allow interchange with all three Northern Line branches.
Sadly, the area in question has a rather sparse population these days and is currently mostly light industry and empty warehouses. What little housing there still is tends to be bungalows and, if your lucky, Brookside-type estates, which Liverpool's planning department still find so agreeable. The long term plans are for this to change considerably with Liverpool Waters and supporting initiatives but these are very long term (we're talking decades) if they're ever realised at all. Currently, even a single station on the Northern Line between Sandhills & Moorfields may be deemed a big ask. It's a shame too, as the five minute frequency on that stretch should be taken advantage of as much as is reasonably possible.