By amount of VRAM
Start from the memory your GPU has. Each page lists every model and the file that fits.
6 GB7 run well · 12 fit in some form8 GB8 run well · 23 fit in some form10 GB13 run well · 30 fit in some form12 GB18 run well · 38 fit in some form16 GB26 run well · 48 fit in some form20 GB33 run well · 49 fit in some form24 GB44 run well · 50 fit in some form32 GB48 run well · 50 fit in some form