Almost every opioid I've ever used has caused irritability at some point.
The least irritability inducing for me was methadone, by far.
My theory is that an opioids capacity to cause irritability stems in part from its strength as an agonist of the kappa opioid receptor (KOR) relative to the mu opioid receptor (MOR).
Not surprising that methadone isn't much of an offender as its MOR to KOR ratio is around 1:250 (meaning it's 250x more specific for the MOR).
Morphine is around 1:175 and oxycodone is something like a very pissy 1:40. I feel perhaps the most volatile and pissy on oxycodone than any other opioid (though I do like oxycodone).
Aside from not being particularly irritable, methadone doesn't cause depression like other opioids as its an active NMDA antagonist. If someone offered me oxycodone, heroin or methadone is take methadone in a heartbeat.