Most around here seem to say that the MC Prostar has a stiff wake at longer lines/slower speeds. Like anything there is a degree of subjectivity to that and if you ski it and love it, who cares?
I recently purchased a 2013 TXi and absolutely love it! Great wake, lots of space, the 5.7 has plenty of power. Plus ZO - not that I am good enough of a skier to really notice the benefits but ease of use is huge.
New boat should in theory last longer, obviously many factors go into that but the 15 is 9 years newer. Less wear and tear.
Personally if you plan to keep the boat a long time, newer makes sense to me. If you want a temporary upgrade that will last for a few years then upgrade again, the MC is probably fine.
Newer boats will have potentially more depreciation. I found that as new boats are insanely expensive that it is artificially keeping the price of used boats higher, at least in some places - like WA state.
I can't comment on the 200 - never skied one. SN makes a great boat and obviously they are popular.
I haven't had any issues to date on my TXi, if maintained I can't imagine I will.