I use a combination of both. Tankers and supply ships are useful to build up stocks on forward supply dumps, otherwise, you have to make many trips with normal ships to build up supplies.
The nations in the 6 Powers Campaign are just getting to the point where they are going to need some forward supply dumps to continue their outward expansion. With their current designs, the exploration groups are finding it very difficult to operate more than 3-4 jumps from Earth. That is very true for the less advanced nations like Japan and Russia, and less so for the Reich and the Alliance, although they are feeling it too.
Kurt
I guess that this is analogous to the historial situation facing navies in the 18/19th centuries where coal depots in strategic locations were needed to ensure global reach (that's one of the reasons why Britain had outposts in places like Ascension Island and the Falkland Islands). Do you look to provide defences for these forward depots or do you assume that a mobile defence is better and use your fleets to ensure nothing gets into the key systems? I would think that fixed defences would be very wasteful in terms of resources but could be seen as insurance for worst case scenarios.
Currently, the Reich and the Alliance are planning on stationing an infantry division or two at their forward depot, along with a cruiser or two. It definitely isn't very much, but the focus for those two powers remains on the solar system, not outside. Of course, currently, both the Reich and the Alliance are operating unchallenged on their primary warp lines, although the Japanese and Indians have done some exploring down both of those warp lines.
Right now both the Reich and the Alliance are trying to figure out how much security they need to provide for their primary colony sites in the Hamburg and the Alpha Cephi system (respectively). Oh, and the Reich is dealing with the devastating realization that their entire stock of missiles, and therefore ships and bases, is worthless in the nebula in the Hamburg system. Major oops.
Kurt