I'm gonna say hands down that I've never grown my own cannabis however I've sampled a fair few varieties on many trips to Amsterdam
The one that really knocked me on my ass was the AK-47 strain from the Dampkring Coffee Shop. That got me so stoned that I had to crawl to the doorway to get some air. Nice flavour too, I've seen plenty of seed companies selling it.
Bubble and ice-o-lator hash is also very potent, go here to look at the kits on offer to make it.... www.bubblebag.com