You consult amplifier, that would be comparable to or better than the LT1124. In particular, the fit slightly lower input current ~1 - 2nA.
I'm not allowed to use IC from Linear
LT1124 is enhanced replacement OP27/OP270 Analog Device now produce AD8671, AD8675 and ADA4004,but none better in all parameters
The differences are very small, perhaps at the level of statistical error and defined measurement conditions, but are