Cubensis are definitely the most "newbie-friendly" to grow so I would (and did) start there. You don't need to go crazy when picking a cubensis substrain (as stated above, a cube is a cube; aside from possibly the Penis Envy strain) or substrate you will use. I'd reccomend PF Tek for your first time, as to get as much experience and knowledge out of actually going though the motions yourself. Once you've familiarized yourself then you can start picking specific substrains to grow (if that appeals to you) and working with different teks/substrates to maximize yield.
As far as the best to grow, I'd like to think having a nice outdoor garden of woodlovers would be optimal, but I need to refine my techniques a bit more before attempting that.
Also, the spores are most definitely legal but some vendors can be shady. Even when I was a noob at ordering such things offline and had no way to verify my source, the first one I found ended up to be legit so I wouldn't get too paranoid about being ripped off.