They're all sophisticated payware models in their original construction and each one comes with its own respective challenges. And make no mistake about it, conversion challenges are the norm for the more sophisticated models.
IMHO, the real question is not which is the easiest, but do you have the confidence and persistence to handle the learning curve for the problematic ones? Your question makes me wonder. In very few cases will you have a model that just won't convert conventionally with the mdlc program. When you encounter this, you might have to do some hex work in the mdl file to convince it to cooperate. Moreover, sometimes they come through with animation problems that can only be sorted with scasm edits. That's one more thing to learn, beyond conventional converting and the time consuming follow-up tasks of tweaking flight models, constructing accurate DP's and CFS2-friendly panels, plus reformatting textures to show properly in CFS2. And KNOWING all of this ancillary stuff is essential to getting a successfully converted model flying in CFS2. Many newbs can quickly learn how to use the DOS commands for mdlc or run the converter using the mk_Mdlc front-end - its simple point and click when you know what to click - but then they get stumped by all the follow-up work involved.
Working with animations in the more detailed payware models involves a degree of long-suffering for a newb, but if you want to play the conversion game at this level you have to get the confidence and the education required to do it well. Freeware FS models tend to be easier all around due to different construction approaches and provide a good learning platform for advancing to the complicated stuff. So, get your feet wet with some interesting freeware downloads, learn the whole process A-Z, then plunge into the premium payware with confidence. Speaking for the experienced types around here, its a lot easier to help you with related problems when we feel that you have a good handle on the fundamentals.
Have fun...
