You can ohm out some of them but since their not on the motor and in their dynamic, it's hard to check calibration (for thermistors, etc).
I'd probably keep the old stuff labeled and in a bag and install new where I could. The caveat is that some aftermarket sensors arent as accurately calibrated as OEM.
MHO.
If the old ones worked, I'd almost be inclined to leave well enough alone. Remember that the computer can adapt a bit to help out some of them, and most are accessible so you can swap them later.
The ECT is the one I can think of that I'd replace. If others are cheap, go for it. If a sensor is more $, you could leave it be.