There's really no such thing as a must-have SP mod from my experience. Your best bet is just to look around jk3files and see if there's anything that you yourself enjoy. Or, if you're lazy, you can look at the top 20 downloads of the week and see what other people are getting.
Sp mods huh?
I like a few different level mods.
The Ladder, Nina series, Jedidojo, Bobo's Jedi Trainer
Those will offer lots of saber combat. Nina series is a good story mod with a variety of combat. The 'Escape from Yavin IV' mod is really large and well done. It is also a pretty good challenge.
There are a lot of different sabers, playermodels, and such that will fit your taste. If you find a model/skin you want to play with that doesn't have sp support you can make an npc file for it pretty easy. Then just use the console command to change into it.
There are also demos of the Dark Forces Mod, and Chronicles mod. I'm part of the Tales of the Sith Lords mod that is sp. We are working towards a demo of that as well.
I've released a beta of a new saber style that is setup for sp. It is a sword and shield style for Link from the Legend of Zelda. http://www.filefront.com/15143815/Link-mod.zip/
Still a beta technically since there are things I want to change still but it is on hold for now.
I've also made some backhand saber style animations, ala Starkiller, for the TotSLs mod. Once I get the latest version updated I'll release the previous version for people to play around with. YouTube - Secret Apprentice 1
That's all I can think of at the moment.
One thing is that there is no sp code so our mods are somewhat limited.
Mercenary has some other mods. He has the Dash Render Resurgence and I think a couple others for JO. I like the Dash Rendar mod played with Kyle. It has a old school Jedi Knight feel.
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