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You need something with very low on-state voltage drop.  That effectively means some type of FET.  Those look resistive when on, as opposed to a voltage source like a BJT does.

You need to look carefully at the voltages when the switches are supposed to be off.  The body diode of MOSFETs and the gate junction of JFETs may pose a challenge.

There are also totally different approaches to charge balancing.  The one I've seen most is to have switchable shunts across each cell.  Those are turned on for the cells above the median voltage during charging.