Need suggestion on single supply rail to rail op-amp to use with arduino uno?

We have no idea what is easy for you to find...

We are just going to suggest parts with no idea if you can get them! Anyway I've used the AD8656,
a dual, true rail-to-rail, 3--5V opamp with very good specifications (very low noise, very high output
current, good bandwidth, very low input offset, etc etc). Its not cheap, and its max supply is 5.5V only, but its
far superior to the LM358 (which starts to flake out above 5kHz or so for large signals I've found).