The "I love growing marijuana" one, Robert Bergman's, seen others saying it's a decent one.
Biggest issue with me has been good old light, and me trying to do things too cheaply and not realising that I needed a hell of a lot more than I had with the first plant did hurt (and the vacation in hospital, a double kick in the nuts, you could say). Second one was always going to be dodgy as I was experimenting with a self-made grow light, I realise the mistake I made so made another light with substantially more power which is above my third plant, now I'm planning an improved version "just in case".
At this moment, as I say, I'm taking baby steps as it's impossible to justify the costs of some of these commercial builds to the missus since income is restricted thanks to me being broken, and since I can't work growing has turned into a hobby just now with the view of making incremental improvements whilst keeping me occupied.
Baby steps, as they say