Freshwater 100% if you want the least maintenance. Salt water, while more rewarding imo, take almost a part time jobs worth of time and effort to keep them thriving especially at first till they get fully established.
Stay away from canister filters, they are nitrate factory's and will end up being your main feeding source for bad algae that will likely make you take down your tank. A good HOB (hang on back) filter like Rob uses will work great, just keep your filters changed. Also partial water change, like a once a month 10% will really help keep your water where it needs too be.
If you are going to use tap water, make sure you have chlorine, ammonia remover on hand (liquid/dry supplement). Makes your fish stay healthy as well as some will help clear out excess iron in the water. Although if you could use a RO/DI unit you would be best off with it.
Over lighting can also be a problem with over feeding.
If you want to go cheap, watch Petco for their $1/g sale where you can go up to 55g. Those are tank only of course. You might watch craigslist though for a full setup of tank, filters, heater, lighting, stand/canopy.
You know what you are wanting fish wise? Community freshwater would be likely the easiest to just stick fish in and let alone but a Cichlid tank would be your most colorful option but dont just go buy cichlids and stick them in, you have to know exactly what ones will work best with others and your setup. Rob can help you there for sure.
Also, biggest help in my opinion is to NOT listen to your local fish stores, always ask online instead. We arent here to sell you anything and will give first hand info instead of info they memorized to sound like they know.