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It will work with practically any O2 sensor. But a wideband sensor is the most useful for tuning. The standard inexpensive Bosch wideband sensor seems to be the favorite.

see Oxygen Sensor

I use the Bosch but only for a rich/lean gauge for tunning the carbs.

Get a 4 wire if you can. Its got heater and ground insulation for signal. Commodore v8/supercharged ones are probably the cheapest ones. I think I have a couple that i swapped out from my ls1 when I was getting error codes. Was a oil pressure sender in the end.

I bought a Zeitronix Zt-2 wide band setup. Not yet installed but in the pipeline. Something to keep in mind is that the wideband sensors have to be mounted upright an after any turbo/ cat and at least 600mm (or something) down stream of the head as they don't like too much heat.

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Get a one wire for the ecu and a wide band kit for your tuning

The 4 wire narrow band sensor has two wires for the sensor +ve and -ve and two wires for the heater (+12v and ground). The heater just means it gets up to temp faster and gives a signal faster. The +ve sensor wire goes to the ECU.

Depending on ECU and set up you can use a narrow band to adjust the fuel while running, but only near stoichiometric, wide band you can have the ECU adjust the fuel across the whole operating range. Downside of wide band is it costs more, needs a dedicated controller (unless it's built into the ECU) is is more delicate. That said you should get the whole kit for $2-300 bucks. The Megasquirt site has heaps of information on how it all works.