VT20 as BLASTO said is very similar(even better than) to ST30 and best part is it is 25K-30K lesser than ST30. So on VFM basis VT20 is a good choice if you happen to get hold of one, as stock everywhere are vanishing. Read this thread and my search to get a VT20 in tamil nadu.
ST30 - lesser crosstalk in 3D , no floating blacks , same filter as VT20 , one 3D glass lesser than VT20 , white peak is twice higher than VT20
But it has fluctuating Brightness (but fixed i suppose)
If you want to save 25K and get something like Bluray player or extra pair glasses , Get VT20 .
one more comaprison
Vs Panasonic TC-P50VT20 - Panasonic TC-P50ST30 Plasma 3D HDTV Review
as for your question ..
since i couldnt find a VT20 for around 75K , I went for ST30. I am not sure whether its worth the extra money , as i myself going to first time own a plasma and i am moving from a 2007 LCD (720p) TV. So anything will look awesome for me..
I don't think the comparison offered on the televisioninfo site is fair to VT20. Here are a few points which seem off.
- Black Level (HDTVTest is the best source i can think of with their Klein meter): VT20 measures 0.009 cd/m2 and ST30 measures 0.028 cd/m2; Incidentally, CNET did a long term test on black level rise on the VT20 and it's final risen black level is still expected to be on par if not better than the ST30.
- As per CNET and also noted by chadb, the ST30 is actually a little dim.