Select between two sources with transistors
If you're selecting between two sources of binary digital data, you should be looking for a digital multiplexer. If you're selecting between two analog signals you should be looking for an analog multiplexer. There are dozens of part numbers of either type available from the major IC vendors, depending on the details of your requirements.

Buying either of these circuits as an IC will probably be lower cost (after accounting for assembly costs) and almost certainly be more reliable and give more consistent results than constructing them out of transistors.