Haha, vague, but I'll bite... To answer your question, most of the time, anything that does the job and isn't some filthy schwag (brown frown) will do the trick. As for particular strains, just about anything that has a name and was well cared for will be accepted as "high-grade".

Personally, I love white widow. It does really well in a DWC and produces some of the stoniest bud you'll ever smoke. But the waiting for harvest... OH god, the waiting...