The informed opinion is that there are good and bad from both civvie and ex-military. Horses for courses sometimes.
However the biggest irony with the civilian instructor is that it is generally the only job a newly qualified CPL can get, so he/she goes into instructing not because they want to but as a means to an end, an airline job. Would that the system be better, in that it encouraged and rewarded the mature pilot who actually wants to instruct. But as has been seen in various magazines etc, it is being made more difficult and expensive for the mature infrequent instructor to keep their ratings, so they are drifting away and a valuable asset is being lost to instructing.
Its the system that forces unwilling instructors into the only job they can get that is wrong.