That is a very difficult question to answer, because there are so many variables. The question would be more appropriate with some background information on your specific aquarium. "Easy" to keep depends entirely upon the parameters under which the question is asked.
For the purpose of the question, I will assume you are shopping for a 55 to 75 gallon aquarium, with a 4'' sand bed, 100 pounds of live rock, a sump, and a good high quality protein skimmer. This would be an average aquarium by marine standards.
The following fish are easy to keep in aquariums 6 feet in length or more, but would not apply to your situation:
Triggers, Puffers, Groupers, & Lionfish. You can add Rabbitfish and Tangs of the Genus Acanthurus and Naso to this list, provided you have a proper quarantine aquarium in place.
With a mature aquarium of 6'' in length, most large Angelfish of the Genus Holocanthus and Pomacanthrus are also rather sturdy. With Angelfish and Tangs, dietary conerns are also an issue. I would also suggest the use of a UV Sterilizer. Banana Wrasse also adapt well in larger size aquariums.
The following fish are easy to keep and more appropriate for aquariums in the 4'' length size:
Basslets, Clownfish, Tangs of the genus Zebrasoma (with proper quarantine), Hawkfish, Dottybacks, Fairy Wrasses and Flasher Wrasses, Anthias, most Blennies, and most commonly found Angelfish of the genus Centropyge. Be careful with Centropyge angelfish, as some species simply will not live in captivity, but most are very sturdy. Ask here before you buy.
The following link may help you with the lists above: Fish Index
I do not think there is a coral for the beginner. I think you need to get your hands wet in the marine hobby first. However, to answer the questions, most soft corals are rather sturdy and easier to keep. Leathers, mushrooms, polyps, etc.