Which is best for underground pipe repair?

[DivingIn]

Which is best for an underground PVC pipe repair? Union, Compression coupling, or Slip (telescoping) coupling?
Union has one o-ring, Compression has two seals, and Slip has 3 o-rings.

 

[Bill1974]

Glued would be my first choice, next would be Compression with two seals. None of the others I would like to use on underground repairs. Also the compression fitting would be pressure rated not just DWV.

 

[Lake Placid]

Glued coupling. I wouldn’t use any mechanical connection (threaded) underground due to the likelihood of it loosening and leaking over time.