1. Sacrifice part 2
2. Ides of March (I know technically Deja Vu all over again in the actual finale but production and narrative wise ides of march is the true s4 finale)
3. Is there a doctor in the house?
4. Comedy of eros
5. Motherhood
6. Friend in Need part 2
For me Motherhood and Ides Of March rank at #1, they truly felt like the end of an era. Friend In Need is a bittersweet one for me so I don't watch it as much.
Sacrifice never felt as a finale for me, for some reason.
As for the others, same thing. They felt like a random episode inserted at any point in the timeline. Adventures In The Sin Trade feels more like a finale. They should've ended season 3 with those and then Family Affair should've started season 4.
This is more a matter of personal taste. I agree with the comment that some episodes do not seem like Finales at all, just denouments and resolutions to previous episodes. They also do feel random particularly in later Xena episodes like the ones in Season 5 and 6. I never liked the series finale Friend In Need 2 so I won't bring that one up. For me the most satisfying finale style episodes which felt like actual season finales to me include:
Is There A Doctor In The House? Season 1 Finale
Destiny
(I seem to recall watching Destiny and then waiting something like a whole summer before the next episode came on, this being on Los Angeles' Channel 5 then known as the WB, so for me Destiny felt like a Season Finale to Season 2.
The Bitter Suite - For me the Bitter Suite is a good wrap up to the Hope/Gabrielle thing, and the reconciliation with Xena. It was a musical episode we all love but it does have the feeling of being a Season Finale Season 3 Finale.
Ides Of March would have made the best season finale ever, and would have preferred it as the Season 4 Finale which would have ideally been followed by Fallen Angel as Season 5 Episode 1. I never cared for Deja Vu All Over Again and I feel should not have come between Ides of March and Fallen Angel.
Fallen Angel has become my all time favorite episode of the entire Xena series now as an adult but having watching this show for the first time in high school, I really loved A NECESSARY EVIL. It was my favorite for the longest time and I thought it too had a series finale sort of feel to it.
I think some of the problem was that they put together too many episodes in a single season. They could have divided the episodes up into even more seasons (more than 6) and always ended the season with those cliffhanger and "resolution" type of endings we see in the episodes I've mentioned.
For me the 2 most satisfying season finale style episodes are Destiny, A Necessary Evil, Bitter Suite and Ides of March
1. Sacrifice: Part 2
2. Ides of March
3. Comedy of Eros
4. Is There a Doctor In the House?
5. Motherhood
6. A Friend in Need: Part 2 (Didn't really like this. As a matter of fact, much of season 6)