Slams aren't the end all be all. Context is crucial.
When draws are reviewed they show glaring variances. When you consider periods of dominance over accumulation and pool of talent.
Borg & Sampras are without a doubt top tier ATGs. Just stop it.
Tier 1: Borg, Sampras, Nadal, Djokovic, Federer, Laver, Gonzales, Budge
Tier 2: Rosewall, Agassi, Becker, Edberg, Lendl, Connors, McEnroe
Tier 3: Wilander, Murray, Necombe, Nastase, Courier
Yeah, no Vilas for me, the AOs are asterisk and his only USO was on clay, common now.
Guys like Tilden and Emerson have too many issues due to the fields they played. Tilden only had to play single matches at the USO during the challenger era despite him clearly being the best tennis player of that period he just didn't have to do as much securing all those titles. Although Tilden is a historical great he's hard to quantify in comparison.