I'm more than a little baffled by the "Jar Jar was better" argument. Jar Jar was not just crippled by bad dialogue - he looked and acted like he was made out of rubber, the character design was overly simplistic (vest and bell-bottoms?), and he never interacted with other characters realistically. What was most damaging in Jar Jar's case, and this is true of most CGI characters, was that the light and shadow did not fit him in the scene with the other characters. This is the hardest part of putting CGI characters in live-action scenes, and it's often responsible for people saying that it just doesn't look right without knowing why. Getting the ambient and multiple-source lighting in the right places and at the right levels so that it hits the CGI characters the same way as the others just hasn't been perfected yet. And in Jar Jar's case, it looked like they didn't even try too hard (a la Roger Rabbit).
The contrasts between Jar Jar and Gollum are just too glaring. Jar Jar has a rubbery physiology with a poorly defined musculature and a uniform-color, shiny skin. Gollum has a papery skin with mottled shades, tufts of hair, scars, and birthmarks - he has a well-defined musculature that flexes realistically with movements. No contest.
Jar Jar has a mostly static face that is capable of exaggerated, cartoony expressions but not subtle changes. Gollum, on the other hand, has an almost-human face that is capable of subtle changes in human expressions (better than the cross-eyed and stroke-victim-like faces in Final Fantasy: The Spirit Without) AND exaggerated emoting. In addition, he has pupils that dilate and contract and he is capable of displaying changes in dominant personality simply by changes in facial features. No contest.
In Phantom Menace, both Obiwan and Quiggon have difficulty addressing Jar Jar directly - when they do, it often looks like they are looking at a point a foot in front of or behind his face. They are obviously trying to focus on a tennis ball where his head should be, but it doesn't work well. Jar Jar's physical interactions with live-action characters are very limited, and they look pretty bad when they happen, so he sticks with interacting with inanimate objects (the pod racer) and other CGI characters (battle droids). Gollum's interactions with other characters are not flawless, but they are much better (a level above what we saw with Dobby earlier this year). Take, for example, Gollum's first scene, where Sam and Frodo wrestle Gollum to the ground and Gollum fights back viciously. The interaction in this scene is quite impressive, as Gollum seems to have real weight and pushes against the other characters, kicking Sam off him at one point. Grappling requires full-body contact on a level that has never even been tried with CGI characters, and Gollum pulls it off with surprising realism. No contest.
Jar Jar never quite fits in with the lighting in SW:PM, and it largely has to do with his very shiny rubber skin that reflects a lot of light. ILM just didn't put a lot of work into the lighting on Jar Jar, though, and he looks like he's standing in consistent ambient light in a lot of scenes. At least WETA made a good effort with Gollum, particularly in his first scene, as he climbs down the cliff in the moonlight. The blue undertones and shadows are just right for the scene. The work is not as good in other scenes (as in Osgiliath) where he seems to be standing in brighter light than the other characters, but it's still light-years ahead of the work on Jar Jar. Again, no contest.
As for supporting noms for Andy Serkis, I don't think that the Globe nominations mean much because New Line's PR campaign for Serkis is just ramping up and focuses particularly on the Oscar noms. I think that it is largely a stunt, serving to make the point that Serkis' work on Gollum is so far ahead of past CGI work that it can be considered realistically for a nomination. I don't think he'll get it (and I don't think he particularly deserves it based on the great supporting roles of this year), but the campaign makes its point well and shows that WETA's work on Gollum is impressive. Even if Dobby or Jar Jar were given better scripts and larger parts, they would be laughed out of the room in any Oscar talk because they just aren't "real" enough for serious consideration of any kind.