One reason they sound worse at the end of the album is to do with the relative velocity of the disc at the outside tracks (Track 1,2,3, etc) versus the speed on the inside tracks (the last few on a side). Result, more sound in less space.
The same issue is tackled with compact disc by altering the speed of rotation as the laser traverses the disc
Also on a turntable the tracking angle error of the stylus is greater at the inside tracks with a regular pivoted arm. Some turntables have tried using a radial (straight line tracking) arm -- as per some old Technics, Bang & Olufsen and a few other brands who have tackled the issue from time to time.
In other words there's a lot more to this than the quality of the vinyl compound or the weight of the disc -- though heavier would tend to be better at absorbing the resonances set up by the stylus tracking the groove.
As for choice of turntable -- there are still many high end brands, mostly European using the belt drive system which allows optimum decoupling of the turntable from the speakers reducing colouration but is prone to wow (speed variation).
Personally I use a belt drive Thorens and a direct drive Technics. Direct drive gives a steady speed which is discernible when compared with belt. But the design is not so good at isolation. The Technics 1200 series model I use is popular with DJs because it has a very solid rubber/aluminium plinth but, above all, because it offers almost instant start/stop. I chose mine for the latter reason when transcribing vinyl to CD-R but was pleasantly surprised by the overall quality of sound.