The Strontium Dog game is excellent. The Dredd game is underwhelming. Both use exactly the same engine, so it comes down to character design and play testing, which the Dredd game fails at.
Haven't played or even read Slaine, but have ordered the ABC Warriors rules - hopefully won't regret doing so.
Pretty much that, although I haven't actually played either the Dredd or Slaìne incarnations.
I got in with pretty much all the SD releases, skipped on the JD stuff (since I have grown a bit wary of Warlord Resin and have lots from previous ranges), and Slàine, if ever, I would do with other (metal) celtic myth figures. Sadly, only played it a couple of times since the universe is so inaccessible to most folks around here.
I was particularly impressed with how the Strontium Dog handled the differences between "named characters" and "faceless hordes", in that the heroes have sufficient oomph to tackle even a larger number of opponents, but will run an increasing risk of running out of steam if overdoing it. Movement, fighting etc. were quick and nicely streamlined while still providing good variety in the various statlines, and the special rules even for the more outlandish characters worked quite well.
Also, the SD figures were excellent likenesses and very well done. Very happy that I bought in on that, whereas I already had lots of JD stuff as well as most what I needed for Slaìne.
I'm in two minds on the ABC Warriors release. This "slice" of the 2000AD "spacetimeline", along with the Nemesis offshoot, has always been my favourite, and I will certainly get the rulebook at least. I am not so taken with them focusing on the Volgan War storylines, although the figures previewed again look very, very close to Clint Langley's art. They're resin, mind, and that may keep me off from buying them.
However, if the rule approach is working out more like in SD rather than in JD, as craig pointed out, I will be very happy.