Worst:
No Q/Guinan scenes in Season 2. There was never any follow-up with them after "Q Who" and "Deja Q", this was the perfect chance to correct this mistake, and they never did.
there was a Q/Guinan scene in S2. It was young Guinan but it still counts.
Best:
All the different Rios holograms
The ship designs from Krause, Eaves, etc…in S2-3
All the stuff in the Confederation timeline
Worf and Raffi as a crime fighting duo
nu-Guinan
The Picard/Ro scene
Liam F-ing Shaw
S1 Laris
Ranger Seven
Scared/sad Riker in S3
Jurati singing at the reception in S2
A classic Connie being at fleet museum and not the Discoprise version
Everything Geordi
Q
Worst:
The brutal killing of Icheb. Don’t mind him being killed just too ugly.
Seven and Raffi as a couple. Just zero romantic chemistry IMO.
Picard now having a tragic back story
Beverly naming her 2nd son after her first husband
Re-naming the Titan the Enterprise
The overuse of STO ships. Especially the fugly Enterprise F
Incestious Romulan brother and sister duo
Shaw dying
Everything Rios in S2 except for him being Captain of the Stargazer
The Soongs looking pretty much identical for 400 years.
Project Khan