i'll also support the cichlid argument for the following reasons. First off is price. if you have adequate filters (you're going to want your filters to turn over atleast 322 gallons per hour), then your only real expense will be the fish. you can get a 50 lb. bag of pool filter sand for $7 and rocks are free if you find the right ones.
also is ease of care and maintenance. the big reason that i don't do saltwater is the time. i just don't have it. you have to constantly watch it and most people recommend using R.O. water, which can be expensive in itself. freshwater allows for more cost cutting. you'll need certain lighting, skimmer, LR, power heads, etc. expenses that you don't have with FW
with a freshwater, once you are fully cycled (fishless) it's pretty much on auto-pilot with a water change once a week. you can have a great looking tank and keep your problems to a minimum with fresh water, as long as you research first. even if you want more of a challenge later on down the line, a planted tank would give you lots of problems to fix
plus, i tend to travel a bit and i like being able to go away for a couple days and not worrying about the tank. even if my fish sitters over feed a bit, i know i'm not going to come home to a crashed tank and dead fish.