Hmmm...I'll take a different route...
Instead of listing the five worst episodes....I will also go by category for each series.
1. TOS- anything where---- a certain--captain--speaks--in broken-----paced----sentences. That is----the ---most annoying----part.
2. TNG- Time Travel...period. About as easy as putting on a pair of socks.
3. Hard to say....I loved DS9.
4. Anything involving those overgrown Oompa Loompas known as the Kazon.
5. Enterprise--tough to say....need to see more, but like what I see so far.
Respectfully,
General Chang
"So the Enterprise is on her maiden voyage, eh? Now that is one well endowed lady. Ah'd like to get mah hands on her ample nacelles, if ye'll pardon the bit o' engineerin' parlance." -Scotty, STAR TREK, 2009