you really need to do lots of reading and discussing before jumping into either - but basic corals need not be that difficult providing you start with the right equipment and species of coral etc.
Do you have a tank size in mind, or a budget?
I would recommend going to a couple of loca fish stores, at a quiet time when the staff aren't too busy, and get them to talk you through things. but do not, I repeat, DO NOT decide to make an impulse buy..... not matter how good the deal, or how nice the shop staff, it is always best to come home and log onto RC and slog it out online for as long as it takes because none of us stand to profit or otherwise from your decisions......
I personally prefer fish. Most people prefer corals, or a mix of both. Which do you prefer?
Really, the main question to ask yourself at this point is what size tank you are thinging of. If it is a small tank, I owuld say go with easy corals and do a reef...... if it is a big tank then fish keeping can be every bit as enjoable and challenging

FYI, I have an 8x2x2 fish tank, no corals.