I haven't seen any of the stuff that Over-Time has done, I am a bit more inclined towards TV Nihon, only because of the vast quantity and quality of the shows they have fansubbed over the years. Although, a majority of their content tend to be more current shows with the occasional dip into the past, but even when that happens, they have to get their hands on high quality versions of the episodes in order to sub them, and then they only give us a little bit at a time.
They are also one of the most consistently organized fansub groups in existence, which is more than can be said for most groups who start on something, get a few episodes in and just give up.
I also love the little flourishes they put into their fansubs, where the subtitles sometimes come alive onscreen, makes it a bit more exciting. And also the little bits of information they attach to certain things at certain moments, in order to better educate people here in the states who may not be completely familiar with how things are in Japan that seem rather commonplace for the Japanese, but may seem rather odd to us Americans.
I admire their dedication, and the hard work they put into what they do, although there is that part of me that hopes they get to work on more classic tokusatsu programs, like maybe finishing up DaiRanger, Zyuranger, and stuff like that. Oh well, c'est la vie.