Hi,
I've considered all of these TV's, the ST30 to me is just to ugly a TV to feel happy buying and I would buy the GT30 (which looks much nicer) but can't justify the increased costs as nobody is bundling 3D glasses for it and I'm not able to afford another £300+ for 4+ sets of glasses.
The HX723 (sony) looks very good in 2D and 3D but again has no bundled glasses on any deal I can find online or in store. however it's price has come down to £629 which you can get price matched at JL.
You can get the Sammy in Comet with 3 pairs of 3D glasses at no extra cost at the moment for either £649 or £699 all in which is very good, providing you get a set which doesn't have the 3D or clouding issues. But having spent many hours researching and reading these forums and being scarred off by the amount of complaints on LG, Sammy, Panny, Sony panel etc I have come to the conclusion that you can read the posts on these forums and never buy a set !!
What I do agree with on these forums is the advice that you should check out as many in store as you can ( which I've been trying to do much to my wife's displeasure), at the end of the day don't take someone else's word as your sole reason for buying a TV and go with what you feel (by demo-ing??) will fit your critera the best.
The sony hx723 I've also seen in JL and at a local TV specialist with demo rooms called Hinchleys (in Cardiff) and looks v.good in 2d and 3d from what I saw.
The LG 42lw550T or 650T looks excellent in 3D and if you are put off by comments that it's not full HD in 3D then I would suggest viewing it as I couldn't tell a difference, the 3D is stunning, the 2D not so much....which is what has pu tme off that model as 2D SD and HD will still make up the most of my families viewing.
Good luck with deciding what to go for though
I'm chickening out for a few weeks to keep an eye on prices and deals especially as all the 2012 ranges will be announced in mid/late Jan by most manufacturers which I hope will see deals for the 2011 ranges appear with bundled glasses or maybe a drop in the overall pricing....
.....and instead will get a new home cinema system (AV receiver , blu ray and speaker package) and get that set up ready for getting a TV in a month or so...just don't tell my wife as she doesn't know yet !