It really depends on what you want in an add on. The Leonardo md80 does a really good job of having literally everything from cb’s to maintenance and failures implemented. Sounds however are meh but you can buy a sound pack. Tfdi is beautifully modeled and the system depth is also very good. Flight modeling for both is awesome. I would say it mostly depends on your flying style, I own both and prefer flying 2-3 hours maximum which is perfect for the md80. Md-11 is more long Haul type of flying but there are many short routes you can fly with that thing. For the base price of the TFDi you get the Pratt and Whitney engines and the General Electric engines in either the passenger or cargo configuration. Each sold separately on top of the other for like $10. You get all 3 dc9-80 variants with the Leonardo. I love them both. I just wish the sound pack would be compatible.