Sure, like most fans I bought my favorite episodes of the Original Series on the two-fer sets that came out a few years back in the early days of DVD. Now, sensibly, Paramount Home Entertainment is repackaging the Original Series as they were meant to be, in three season box sets. (The first comes out on August 31, with the others to follow in the next few months.)
The first season, for me, is still the best primarily due to the extraordinary run of great episodes that closed out the show's rookie year. However, as these are shown in air date order, you have the thorny "The Alternative Factor" nestled amongst such roses as "The Devil in the Dark," "Errand of Mercy" and "The City on the Edge of Forever." For my money, the end of Season 1 is as good as TV gets.
Speaking for the completists out there, I know we are all anxiously awaiting that other series, also originally known as Star Trek — the Animated Series!