Be careful what you wish for. Half-speed mastering is but one in a long list of items that can give improved sound quality. Fleetwood Mac Rumours is one of my all-time favorites. I bought the original vintage LP, and then later the Nautilus Half Speed Mastered. For years could not understand why the original was better than half speed mastered. Until one day I noticed the Nautilus was digitally remastered.
Another thing that tends to make for improved SQ is speed. So when a 45 RPM version came out I bought that and sure enough, blew away the Nautilus, better even than the vintage copy.
The best then? Not so fast! Not every copy sounds the same. Tom Port cleans and listens to dozens of really good sounding copies then charges a small fortune for the cream of the crop. These he calls Hot Stampers and so out of all my four copies of Rumours the White Hot is by far the best- even though it is really just a vintage run nothing special pressing.
In other words, you cannot tell anything really by half-speed mastered, 45, 180g, or any of that. It ain't quite exactly all luck of the draw, but it sure plays a bigger role than most care to acknowledge.
Are we having fun yet?