There is no way offlane is the hardest roll. Especially in this patch. For starters all you are expected to get out of lane is some levels and thats it. On top of that all the offlaners now can jungle or pull so they are guaranteed farm (unless you are picking bad offlaners which is then your fault).
Poor support is not nearly as difficult as it sounds. In my ranked games I normally end up playing the hard 5. All wards sents and it is fairly easy. The only thing you have to do is not feed and you just play heroes that need to get their spells off so farm isn't a problem. Not to mention the introduction of tomes has made it even easier to get levels.
Safe lane is the easiest roll IMO but on a scale of 1-10 it would be 9.9999 repeating. Although you have literally two people protecting you most of the rest of the game will be entrusted on you to carry. Your decisions not only positioning and farm rotation wise but also item choices which can be very difficult and hard to know if you are right or wrong, even when you win or lose (see EE)
Farming support in most cases in just someone who gets to pull as neither support should be soaking experience from the carry. Although you are not "poor" (you are) with that extra money comes more resposibility. You will be expected to always be on time with rotation to use the items you have purchased to either set up kills or save cores. If you mean heroes like Enigma who are insane junglers they are a completely different beasts which I could keep writing about but don't want to. More often than not now a days this is just some jungler or a roaming hero ie Bounty or ES
And how the fuck can you put mid lane as the easiest ROFL. I will state again that I am a support player. Mid takes BY FAR the most laning mechanics and map awareness. You NEED to come out of the lane with significant amounts of farm often dodge ganks by the supports. You have to make the same difficult choices a safelane player would make while making plays with the significant amount of farm and XP that your team as entrusted in you. I am only 4.7k and I have played support and offlane with 6k+ average mmr games. I would never take mid in these games because I WOULD GET BLOWN THE FUCK OUT.