Your electrical system does not much care, but the old plugs require higher voltage to fire and tend to flow slightly less current while firing.
Most folks agree that on e36s, it is best to stick to two-electrode plugs rather than four. I like Denso and NGK. If you get Bosch, check the box to make sure they did not come from China or India.
$3 plugs work just as well as $10 plugs for the first 20k miles. After that, the exotic metal plating on the expensive plugs starts to earn its premium price.