Since you mentioned that your custom rack might not be able to hold a too heavy tv and you can't tell the different in terms of their PQ, then the weight of the tv might be the deal breaker here. 55" LED TV seems to be a suitable choice as it only weight about 32kg compared to 60" LCD TV (60+ kg), better energy saving some more.
Save some money for other stuff as getting 3D tv is too early at this stage where price is sky rocket high and 3D contents now are not many with premium price to pay for unless your pocket is bottomless then it will be a different story.