It depends on what you want to say. Use adjectives to describe how they are now and use present perfect to describe what happened to them in the past (in the context of the present time). Ex. If someone has married, they may not be married now. If a man died and was then brought back to life, you could say "He has died" but not "He is dead" (unless he died again). The difference between present simple and present perfect is an important one.

"He has died" means it just happened, but isn't used frequently. "He is dead" means it has happened sometime in the past. The news might report "After a long illness, John Smith has died." If it weren't "news", you'd say, "John Smith is dead."