Which O2 sensor?

[Jimmy2007]

Hi everyone,
Audi A3 2006 1.6 8V sportback petrol manual.
One of my O2 sensor has gone bad.
A scan indicates the following:

O2 sensor negative current control circuit bank 1 sensor bank 1 open

Is it the pre cat or after cat?

Also, don't know if relevant but the following codes are there and can't be deleted, even temporarily:

P0380 glow plug/heater circuit A

P0780 shift error

What brand of O2 sensor do you recommend bearing in mind that the car is 20 years old and won't need to last forever?
In other words, are the cheap ones ok?
I see Ridex on *******.
Thanks