I'd say the most potent I've tried is White Rhino. I have a mostly Sativa (87.5% from what I read) plant (Durban Poison x Skunk #1) growing now, along with ten clones from the single mother plant that's flowering. I've never had enough Sativa pot around to fully judge how much I like it or not in comparison to the super-Indicas. Hopefully I'll like it better than White Rhino (since I'm close to out of that anyway).

One strain I just love is Nirvana's AK-48. I know it's super cheap, and very easy to grow, but, well, I just love it! Some people really really like Dr. Pepper or blue cars or Dr. Dre or whatever. Well, I'm like that with AK-48; it just hits me perfectly for some reason. It's potent, but not the most potent. It has no interesting color characteristics, no unusual taste. I'm sure other people will scoff at my saying this, but what can I say, it's like me an AK-48 were a match made in heaven. Unless I prefer that mostly Sativa strain I'm currently growing, then AK-48 will remain my favorite. Yes, I prefer it to any diesel or blueberry or purple I've tried, or anything else. Kinda handy that the strain I love, that hits me just right in every way, just happens to be so cheap and easy to grow; no complaints about that here!