They're all great.
"Better" is difficult to define because different people have different needs or different requirements. For example, if you need a fully automatic turntable, the SL-1600 Mk2 would be better than the SL-1200 Mk2. And I seriously doubt that anyone could hear any audible difference between them. If you don't need or don't want an automatic turntable, the SL-1200 Mk2 would be better. The buyer's decision should be based on which features they want or need. ALL of the turntables in that series are capable of outstanding sound quality.
What do dance clubs and classical radio stations have in common? Technics Direct Drive.™