Good marbling: Having some fat is beneficial since it dries out much slower than lean ones. But too much can be bad for your health, too, so trim the excess ones if present.
Fresh: As a rule of thumb, get only the fresh ones that have nice color! The meat must be dry, too, not slimy or dripping wet.
Thick: It’s best to get thicker ones if you want rare to medium-rare steaks, because the inside will cook more slowly while the outside is being charred.
Tenderness: For flavorful and tender cuts, opt for tenderloin or ribeye. But these are more expensive than tougher cuts like flank or skirt, for which this marinade works best!