The two candidates you have listed are VERY different aircraft (HP, airfoil design, cabin ergonomics, etc). I've never owned or flown a C180, but I have had numerous conversations with Cessna owners and A&P's about ownership costs before (and since) buying the Maule.
The Maule is known as a fat Super Cub. It fits right between a Super Cub and the C180, although they can have similar payloads. The Maule is cheaper to keep. Annual costs and parts are cheaper and more than offset the cost of increased insurance premiums (Insurance premium rates are based on fleet size; Maule has about 1400 active aircraft and Cessna has a LOT more). The Maule will out climb a Cessna (HP and weight the same) in high density altitude because of the the airfoil design. That same airfoil difference between Cessna and Maule will allow the Cessna to cruise faster. The Maule family is alive and well and still make and support the same airframe they introduced in 1962. The C180 was discontinued in 1981 and some parts availability can get iffy. The fabric is employed from the windows aft as the rest of the aircraft is aluminum and composite. The fabric used in the early Maules was Razorback (fiberglass cloth) until 1981 when they switched to Ceconite. Although partly fabric, they are very durable, are easily repaired and will last a very long time versus the older covering systems used in the 40's and 50's.
We use the Maule to travel 1500 NM (round trip) regularly and find it a good cruiser. It also gets off the ground in 300' light and 600' heavy. It gets off at less than 800' in 9000' DA at gross. We haven't used the back seat since we bought it as we fly two adults, a 100 lb German Shepherd, luggage and supplies, most of the time at gross. When light, I have a blast with it

. Our most recent trip we averaged between high 7 to 8.25 GPH ROP. Since it has 4 doors, I consider it our 1/2 ton crew cab. The cargo door opening is a huge plus to many.
It really depends are how you define what you need your aircraft to do. There are big differences between these aircraft and although the buy in may be similar, the fit is different in some applications. Carefully consider if the extra items the C180 is capable of justify the additional operational costs. And, as has been mentioned here earlier, the Maule is available in 160, 180, 210, 220, 235, 260, and 420 SHP
