GW sprays work great but I don't have easy access to a place I can spray them and they stink up my flat! However it's the toughest primer I've used. I dare say other aerosol primers will also be as tough.
I also like Citadel Imperial Primer. If you are used to the black spray then the finish is very similar and it's pretty much fool proof so long as you shake it very very well. Jab, stab and smash on 2 thin and undiluted coats and it will self level into a brush stroke free detail hugging layer. This isn't as tough as aerosol but still takes effort to scratch off.
I've also been having success with Vallejo Polyurethane black and grey primers. I'm struggling with the white though. Out of the airbrush no problems, blast on a couple of thin coats - job done. However it's the most fragile primer I've used, so got to varnish with this one IMO. Tends to hug details better than GW spray IMO.
In general aerosol for a tough finish achieved quickly, brush on retains the most detail but is slow, airbrush is fast and good details but not so strong.
In reference to GW paints it's annoying how I have 2nd edition pots (circa 1993) which are perfect condition yet everyone complains about the seal on the new pots... If it aint broke fix it until it is
