Ahh, VCC(5V) - 1.5V = 3.5V (so I can read from 0 to 3.5V)..
I thought of LM358 (due to how common it is), but can't find in the datasheet where it is high impedance (i.e. like the JFET input in the TL072).
I need the high impedance so that we don't take current from the circuit being monitored.