Hi prateek_k_chd,
Yes TI, LT (Linear Technologie) National Semi & most ADI (Analog Devices) & so on are usually very generous
What better is:
depends every time from some factors:-(, then you can select a butyful IC for an apps, but in your production is (for exampl.) too expensive, you can not have in a package styl...
You are right, at pAmpers is Board (&cable)LEAKAKAGE is a real PROBLEM!
Input pins are to guard(please refer to datasheets), you must see how you can put some better isolation, teflon, under solderpoint for In-pins on your PCB-IC & what kind of cable can you use!?
Cables do not do leakaging, but they are noisy too in so an application...
You must be carful with Offsetvoltage (& datasheet specifications generally:-() too!
Opa129 has it up to 2mv(at 25Cels.) but in temp-range & with your amlifying factor it can be very much.
Can you accept an outputoffset at ca.300mV?
Same over Ibias; the 100fA is tur as typical, with some parameters, but if you have for exampl. lot more powerdissipation (Load effect), then it will be rise up to ca. 30 times...
OPA124 is surly cheaper & if its paramater are enough good for your aspects-clear, thes is to select.
After montage-tests please make washing your PCB, than handsweat is the most wors stoff(+dust & rest of soldering), your enemy, for your application!!
Tnx for your points too!
K.