Season 4 highlights:
"Revulsion" - Occasionally Voyager attempts a good old-fashioned horror story, and this one of a murderous hologram is just the ticket.
"Scientific Method" - The crew of Voyager begin suffering mysterious symptoms, and it's up to the Doctor and Seven of Nine to discover the sinister cause. The extremely sinister and self-righteous cause.
"Year of Hell, Part I & II" - Voyager faces continual disaster for months, losing life and limb before learning that the cause of the terrible, horrible, no good, very bad day(s) is a genocidal monomaniac with a ship that can alter time. I like to think that Chakotay's willingness to cut the guy (Kurtwood Smith!) some slack is a reflection on the Commander's endless devotion to his own Captain Ahab, aka Captain Kathryn Janeway. Kathy gets her crazy on in these episodes, and as usual wins the day.
"Waking Moments" - Mostly I love the nightmares you see in the first ten minutes of the episode. Do Vulcans dream of impassive sheep?
"Message in a Bottle" - The crew gets a chance to use alien technology to contact home, and for voodoo reasons they can send the Doctor to Starfleet more easily than a Facebook poke. Still, we get to have fun watching the Doctor interact with a more advanced EMH (Andy Dick!) in the Alpha Quadrant.
"Hunters" - In struggling to download the messages that Starfleet has sent after the Doctor's away mission, the crew encounter the Hirogen hunters and struggle with mixed emotions about hearing from home. (But seriously, why is Starfleet communication tech so terrible? They are eternally buffering!)
"Living Witness" - I debated whether to put this in the highlights or the losers category, but in the end decided that its storyline is a bold standalone. The Doctor is entertaining as always (his assessment of Tom Paris, for instance), and I love a good Rip Van Winkle storyline, plus evil crew doppelgangers! My only hesitation about this ep is that if you try to cast the Kyrian/Vaskan conflict in an American setting it is problematic, to say the least.
"Hope and Fear" - Voyager's chickens come to roost in a way. The gift of a magnificent new starship, apparently from Starfleet, is such an obvious Trojan horse that Janeway is rightfully skeptical. I liked this episode for asking the question that was avoided in Scorpion, season 3.
Season 4 losers:
"Nemesis" - The ending is the only redeeming part of this slog through some alien conflict I don't care about. It's very difficult to get invested in one-off characters, even cute little girls with bad haircuts.
"The Raven" - Seven has PTSD from her time with the Borg, and it manifests in unusual ways. Unfortunately, in boring ways.
"Concerning Flight" - Again with the lame holocharacters. I couldn't care less about Fake da Vinci's existential crisis, and wish the Captain had just turned him off and put the mobile emitter in her pocket.
"Retrospect" - Suffers from the same problems as "The Raven." Am I the only one who finds it uncomfortable to have Seven make a false accusation of being "violated"?
"Demon" - This story isn't compelling, but it does directly tie into to the later, heart-wrenching "Course: Oblivion", which keeps it from complete ignominy.