An incident has come up that gives Games Workshop Water Effects an edge over Woodland Scenics Water Effects. It's about bubbles. Observe:
On the left you'll see some bubbles that have come to the surface. The GW Water Effects is thin enough that they float to the top, and I just popped them with the end of a toothpick. GW Water Effects always seems to let the bubbles out (most of the time they pop on their own, in fact). On the right you can see a bubble stuck at the bottom of the Woodland Scenics pond, and it won't come up. This is typical for the WS product; the bubbles tend to stick to the bottom. I don't know why that is, but I have to decide whether I want to dispatch that bubble by shoving a toothpick in there (because the resin is already hardening, it's likely to leave a permanent mark).
Advantage: Games Workshop.
(p.s. The Woodland Scenics stuff does look very watery at this point, which is nice. Still being in liquid form probably has a lot to do with that)