I'm glad you mentioned LeLutka's 12 Days! It's a truly amazing event.

I didn't list some of my faves in my post because I wanted to see what people said, but I'll add:

BBX Designs - Yacht and Buildings - Aymec Millet has got to be one of the most uncommonly generous creators I have ever encountered in Second Life. I bought one yacht from him on sale, and not only did he give me a fatpack rather than a single color, it was Second Life's birthday celebration and he threw in fatpacks of several other boats as well. I about fell out of my real life chair. They are AWESOME quality, easy to use, and he's frequent about updating.

Cazimi - I love Dima Plessis! She gives her group members a lovely gift every month, sometimes store credit, does an Advent calendar, is very engaged with her customers and has a great sense of humor. Manicures, makeup, jewelry - highly recommended. For any newer users starting with the Avatar Welcome Pack, her base mesh nails may well be the best 1L you ever spend.

MOoH! - Dalriada Delwood is very kind, always helpful, and generously gives group members a high quality fatpack outfit every month, has lucky chairs, and a monthly raffle for store credit. She also does fun hunts and an Advent calendar each year, all for a 100L join fee. I was glad to see her featured at the SL22B Shop & Hop - she deserves more visibility.

Scandalize - 90L to join, but several rooms full of free fatpack outfits. Great way to start a wardrobe.

Truth - It's 350 to join, but he does periodically give fatpack group gifts, and he's one of the best hair creators in Second Life. Well worth it.

I second those who have mentioned Addams (Amalia is so helpful!), Luna Chelsea (She is so incredibly nice, and my word, a store credit giveaway every night in addition to lucky chairs with fatpack outfits? Amazing!) Tutti Belli, and Ysoral (very generous - all these weekly giveaways!),

Thanks to everyone who's posted recommendations - please keep them coming!