Go for inferno for sure m8 , and i'll tell you why . With inferno you will start getting paragon levels and that will give u 3 % gf per level . Atm im around lvl 34 , and together with 1 chest piece and Nephalem i reach 196 % gf with my Inferno farming Barb . Im currently farming Act 2 Inferno , and i think im usually at around 200k gold / h , and im only talking about the pure cashflow from gold drops and vendoring , not from selling the rares / legenderies. Act 1 inferno with my current level and gear i would probably hit 250-300k g/h .
I have never tried botting with anything except barb tho tbh. While farming Act 1 / 2 Inferno i hadnt spent too much gold on gear , i think 500k- 2 milion per piece , probably 10 mil for the whole set . I recently tried to upgrade him abit to try Act 3 so i bought 4-5 new pieces for 3-5 milion each , including a stormshield and a Helm of command , and he can clear the place with few deaths here and there , but it goes quite slow, so he actually picks up alot lesser lvl 61/62/63 rares per hour doing act 3 than act 2 .
To sum up . Stop doing gf runs in nightmare , its not worth it anymore. So your left with 3 choices : Either Act 1 Inferno , act 2 inferno or act 3 Inferno . Facts : You can easily gear a char up for Act 1 inferno , and you will probably be hitting at least 150-200k g per hour only from the gold from mobs + vendoring blues / rares from the very start. With each paragon lvl the gold/hour will be increasing ( and the leveling goes really fast ) So together with the rares / legendaries , definetly more gold than your standard 250k/hour you doing now. Act 2 needs abit more gold to make it worth farming , out of my head i would say 15-20 million and u got something really nice going. Now , i personally believe ( i might be wrong ) that even if u end up spending like 30-50 million , you will be looting less 61/62/63 ilvl rares per hour in act 3 than in act 2 , making the only reason for doing act 3 the better legendaries that u might get.