In terms of potency Cubes are cubes. More potency requires a more nutrious substrate in my opinion. Some people say different strains of cubenisis give different feeling trips, you know like some a more energetic trip and some more of a relaxed trip. Since it's your first grow I'd go with mycobags, it's alot simpler than doing jars you have to sterilize yourself. Just shoot it up with spores or lc, put it in a dark warm place, and forget about it. Another great thing about these bags is that you can fruit invitro and still get decent results. Just drop the temp. a little bit and give em some light and in a few days you have pins. Then next time you can move on to more advanced growing. Like spawning to a bulk substrate and doing casings and what not. For spores I would recommend ralphstersspores.com, $15 a syringe and if you know the strain of the month you can get another one for free.
Wow this post has gotten alot longer than I intended it too lol. I better quit my senseless yammerin and smoke a fatty.
Best wishes on your first grow!