ATR's and SAAB's are cheating being proper baby airliners (Part 25). The 19 seat aircraft (commuter category) are an interest example of different design approaches to a problem: Beechcraft 1900D: Best cabin about, good block time due to high climb rate, but high empty weight & fuel burn. Fairchild SA227: quick, cheap and cheerful. nosily as hell, cramped, good example what happens when you take GA sheet metal design abit far (lots & lots of little cracks). they have a 35000 cycle life and probably struggle to get there. Random fact, they have bare metal on wings to meet lighting strike requirements. Jetstream J31/J32: little brick outhouse good for 90,000 cycles due to bonded aluminum. 3 abreast seating means the cabin is too short to separate cargo and passenger loading which seems to drive operators to the belly pods more than anything else. Has that lovely English feature of the spar not stepping down in the cabin (does this mean the design team lived in 300 plus year old houses and didn't think stepping over a beam was anything of note). If only someone would build J31's with a couple of fuse plugs and give it a cargo door.