For those making the transition to the US for employment, the best coverage typically available is the group healthcare plan through your US employer.  Typically, the larger the employer, the better the health plan.  However, as with almost any healthcare plan in the US , be prepared to pay by cash, check or credit card a "co-pay" for any doctor, lab, x-ray visit, etc.

For those hoping to retire before age 65, you must be cognizant of the fact you will be without healthcare once you leave your US employer unless you are employed long enough to qualify for retiree medical benefits.  The situation is not the same as in Canada where you automatically qualify for Provincial healthcare coverage provided you make the monthly premium payments.  There is a government law (called COBRA) that allows you to take your employer health insurance benefits with you for up to 18 months after you leave as long as you take over the premium payments, which tend to be very expensive.  If you are not eligible for retiree medical benefits, you will have to obtain an individual health insurance policy.