I know this is a rather broad statement, but if you like chemistry more then biology, go with a reef. imo with fish you have to deal with alot of deseases and diets and husbandry, which fish gets along with this or that fish. While still having to deal with alot of the same pests a reef does. with a reef alk cal mag nitrates phosphates are a real concern and have to be addressed in one way or another. Time and dedication wise fowlr gives you more "slack". you can go a couple extra more days before changing out a filter or doing a water change. with a reef, when the filter is scheduled to be changed , you'd best do it. Reef is more testing and more params to watch and you definatelty cant go slack on watching the nitrates. So a reef means more dedication. Money wise reef is going to cost more to maintain, you have to change light bulbs if your not going with led. water changes are a must to keep nitrates and phosphates down , unless you get into one of the high tech (experimental imo) processes and it might not even work for you. fish you have to feed, alot of corals can go a long time without feeding. Ive read some posts that people dont even feed their corals. with a Fowlr tank you will basically buy the population and thats all you will buy untill one dies, you can only have so many fish. With corals you can keep buying and buying and buying(lol), keep them small by pruning and fragging and then move on to the next bigger tank (lol) imo fish are rather boring. they swim back and forth, you dont notice much growth until a length of time goes by most wont propogate and they die. corals can be kept for a very very long time and you get excited when you run to the tank and see this or that has its polyps out. or when you see new growth in this one or that one or the frag you cut off last week is starting new growth. I know this is very general and will inspire alot of argument , but this argument worked on my wife.