Just a quick doubt!
As I undertand bsnes is the best SNES emulator and after some testing for me bsnes_mercury_accuracy seems OK but I would like to get some opinions!
Should I stick with the one that is closest to the original bsnes or mercury is okay? What should I do? Anyone can explain the differences?
For me the most important thing is accuracy and I just want to play the closest as possible to the real hardware!
The *mercury versions should be a little faster than the regular ones due to some compiler optimizations. They also have some core options that will allow you to use less accurate but also less demanding HLE for the special chips, which is much faster than the standard LLE path (Mega Man X 2/3’s cx4 emulation is particularly demanding with LLE). This also removes the need for having the special chip images in your system directory. Other than those things, the mercury cores should be identical to the mainline cores.
For accuracy/balanced/performance, accuracy is something like 40% slower than balanced for the benefit of one (crummy) game called A.S.P. - Air Strike Patrol.
Thanks for the help again 
For what I understand mercury gets the best of both worlds with cool options so I will stick with it!
Besides the performance increase, I would also go with the balanced version of mercury since it works better with CRT shaders. It’s because the accuracy core always outputs 480 lines while balanced does 240 except when high resolution mode is used.
I personally use bsnes-mercury-balanced and it works wonderfully with CRt-Royale shaders and demanding configuration options like frame delays etc.
Did not tested a lot but bsnes-mercury Accuracy is working perfect here playing Super Metroid with the wonderful CRT Royale!
I will stay with my approach for now and use the highest as possible till something gets messed up