this is a tough question...like comparing todays cars to a 55...of course, with technology, todays cars are better, but some of those old cars broke ground that changed our lives
so too star-trek
the original was ground breaking in so many ways, and it actually changed some peoples lives...for this, nothing can come close, can it.
then again, if you lay those things aside, the original cannot come close to what's come since.
the next generation had some of the best writing in the history of television, yet was flawed in casting...ha...number 1? a joke, the doctors son?..a joke...still worth watching to be sure.
ds9...also excellant writing, a little too dark for my star trek fantasy though
my favorite giving side be side comparisons was voyager, casting, writing, effects, all combining in concert
I don't care for the current version of the franchise though