[Nerull]

My personal suggestions:

Kelsey: solid mod. Good alternative to Annoyman as a romance (put both in your party for extra fun). Not overpowered, but a solid member of the party. Much recommended.

Oversight mod: Among the options for this mod are: fixing the alignments of the NPCs to be more in line with their behavior, fixing the clerics so that chaotic clerics cannot worship Helm (who is diehard Lawful Neutral), allows monks to get the cleric stronghold instead of the fighter stronghold (and gives them other high level abilities than the fighters get). You can pick the components you want.

Imoen romance: This is a pretty well-written romance, but does change her personality somewhat. I like it personally, but if the thought of playing a romance with another woman (especially one that is your "sister") turns you off, you might avoid this one.

Banter packs and Flirt packs: Highly recommended! They add so much to the game it is not even funny. You definitely want to try these.

Ease of use: I use this only to get rid of some of the annoying things in the game ("you must gather your party before venturing forth"). Avoid the stuff that is pure gouda (i.e. overbalanced shapeshifter, etc.).

Improved Hell Trials: this is highly recommended if playing neutral. I really hated having to take the "good" path through all of the tests when playing a true neutral cleric.

I try to avoid the Weimer mods as much as possible. I personally do not play the game for it to be overpowered or extra challenging. I play it just for enjoyment and NPC interaction, so difficulty means little to me. However, if you do like challenges, then try Tactics, Ascension, and the other "Improved" fights.