Which kind of health plan is for you -- Traditional health insurance? A health maintenance organization (HMO) with prepaid care by the HMO's own staff doctors? Or an independent practice association (IPA), a prepayment plan with many doctors participating from their own offices?

Your answer may depend, first of all, on the cost.

Federal workers are currently getting detailed cost and coverage information on many plans during the government's annual "open season" for health plan switching. Workers in private firms with 25 or more employes now must get a similar choice of plans yearly, including a selection of qualified HMOs.

Costs of plans vary widely, depending often on whether you buy "high option" or "low option" coverage -- high option costs more and covers more -- and any extra features, like payment for prescriptions, if available. Current Blue Cross-Blue Shield high-option traditional insurance costs the federal government and participating employes a total of $53.04 every two weeks for individuals, $116.04 for families; low-option, $26.47 and $68.84

HMOs and IPAs often cost more, but costs vary widely with services. The total payment every two weeks for a single federal employe ranges from $33 to $45; for a family, from $73 to $109.

But the federal employe pays only part of the cost (see table above). The government pays the rest. Private employers pick up varying shares, from zero to the whole thing.

If you have to buy traditional health insurance as an individual or family, not part of a group, you may pay much more for less coverage. If you can find an HMO to accept you -- it may depend on your age and health record -- you may do far better.

Though HMOs and IPAs often cost more than traditional insurance, they typically cover more. Almost everything is covered for a fixed payment. Depending on the plan, exceptions (or extra-cost items) may include prescriptions, eye and hearing tests, blood, speech therapy, artificial limbs and appliances. Some IPAs charge $5 or $10 per doctor visit to discourage too many visits.

Your health status may also affect which plan you choose. Young, healthy, childless persons may pay more for HMO membership than they get back in care. But the person with recurring ailments that require many doctor visits or hospitlization may come out way ahead. So may the family with young children who are forever requiring a trip to the pediatrician. HMOs generally cover well-baby care and immunizations, which traditional insurance usually does not. Many also offer periodic physical checkups.

HMOs give you a stable, planned way to budget health costs. They do virtually all the paperwork. You seldom have to submit claims.

In an HMO under one roof, you can usually count on finding specialists present or on tap when needed. Your care, if the plan is a good one, will be coordinated under the one doctor who mainly looks after you and knows you.

If the plan is a good one, it should also have a regular review mechanism to monitor its doctors' performances and eliminate any bad apples.

Those "ifs" can sometimes be large ones. There are also possible HMO minuses.

They don't always work the way they should. One hears from dissatisfied HMO patients as well as dissatisfied patients of doctors in private practice.

You may not always see a doctor. Some HMOs use many nurse-practitioners and physicians' assistants to see patients. And some patients find they like this -- the care may be personal and unhurried.

In some plans, you may also have trouble establishing one doctor as "your doctor." Even when this seems established, you may find it hard to get an appointment in a reasonable time and you may too often have to see the "first doctor available."

Most of us like a doctor who will continue to care for us over the years. Some HMOs have been more or less revolving doors for young doctors just getting started and looking for places to practice on their own.

With more and more doctors graduating from medical schools, that may now become far less true. Competition among doctors has made an HMO job an attractive alternative to setting up an expensive practice, and all the more so as more and more patients choose the HMO option.

For the first time, HMOs are becoming a part of the established medical scene rather than lonely offshoots.