I agree, I take Jan in my party over Astarion any day.
And Mazzy, love her.
Mazzy gets a no from me I'm afraid

. In fact, I've gone the other direction for her than for Jan and come to like her less over the years, and now find her really quite annoying which I don't recall doing initially. I still hope she actually got to become a full paladin when the rules changed, though

.
Yes Mazzy is one of those NPCs who really benefits from mods like Mazzy Friendship

Some classic Jan interactions (with Keldorn & Mazzy) :):
Keldorn- One must maintain constant discipline and remember the four principles of virtue...that is my motto and everlasting burden.
Jan- Virtue, eh knighty?
Keldorn- Indeed, little one- ’Tis not virtuous to refer to me as ’knighty’-
Jan- Another human with his shorts in a knot. But I digress. Anyway Keldy, my mother wrote a book about virtue.
Keldorn- Did she?
Jan- Oh, yes. A book on the virtues of erotic love. "Sins of the Flesh Golem", it was kalled. Excellent sales in the paladin’s spouse market.
Keldorn A wholly inappropriate jest, jan. You should be ashamed.
Jan- It is not a jest, I will send your wife a copy, if she doesnt allready own one.
Keldorn- Never speak of my wife, gnome. Your lack of respect is appalling.
Jan- Ah, now I see. One of THOSE.
Keldorn- It is not your place to judge my affairs. You must learn to respect your leaders.
Jan- I do respect my leaders. This has nothing to do with them. This reminds me of the chapter where the paladin first makes passionate love to the flesh golem. What a beautiful scene…
Keldorn- Begone, gnome, lest my honor demand I perform acts that you shall regret.
Jan- ’Fleshy, honey,’ the paladin said. ’Yes baby?’ said the golem…
Mazzy- Jan, I find you quite the enigma. This adventure has yilded us a crop of useful magical items and yet you turn your considerable powers to the never-ending quest to create the perfect turnip peeler.
Mazzy- How can someone who’s so clever be so shortsighted?
Jan- Well, Mazzy, you’re really asking two questions there. My shortsightedness was passes on to me by my dear departed father. I was born with the condition and I’ll thank you not to stare! As to your other question, it takes me back to my carefree days as a deckhand on a turnip mechant galleon. We sailed for distant Waterdeep, we did, braving foul seas, foul tempers and a desperate band of turnip pirates.
Mazzy- You are mentally incapable of answering a straight question, aren’t you gnome?
Jan- ’Twas on a cold winter’s night near the beginning of the Great Underwar Shortage that we set sail. I danced naked on the poop deck, which was the custom at the time. Well, my nose and other extremities were getting a bit frosty so I gathered up the tatters of my poor, abused, underwear and headed to the crow’s nest.
Mazzy- Shutup, shutup, shutup, shutup!!!
Jan- Well, I never! You did ask, after all.
Mazz- SHUTUP!!!!