WITH 20 or so different local governments of varied sizes, shapes and responsibilities operating in this metropolitan region, you don't find a lot of agreement on what the best structure of a legislative body should be. On the contrary, politicians and voters around the region are constantly rearranging their councils and boards in an attempt to make them more representative, less parochial, more regional, more neighborly, more black or white or urban or rural. Last week, this sport returned to Prince George's County, where the council took another in a series of looks at itself before backing away from any change for now. The council might well take yet another look; some modifications in Prince George's would help.

As it happened, some of the same groups that campaigned hard and successfully five years ago for approval of the current council structure -- members elected by districts -- are now calling for a return to a version of what they used to think of as the bad old days, with members running countywide. At that time, leaders of black organizations sought the by-district elections as a way to elect black candidates whose chances of winning countywide were slim.

But last week, these groups found themselves aligned with developers and others in support of a bill to place on the 1988 ballot a charter amendment to allow four of the nine council members to be elected at-large. One of the four seats would be held by the council chairman. The difference now is that blacks can make up a majority of the voters in a Democratic primary. But the proposal was voted down amid concerns that costs of running council races would soar if developers and big business teamed up to finance at-large candidates, and because some saw it as return to political bossism.

Our preference the last time around and now is some sort of combination of at-large and district seats. Election of all members by districts can produce destructive parochialism and divisiveness, while an all at-large council can submerge certain minority interests (including the Republican minority in the county) in favor of a single-party organization. No combination of numbers guarantees good government, of course, but the mixture of representation has served many jurisdictions better than swings from all-district to all-at-large.