There is only one sim I can really say in answer to this though there are lots of sims that I love. But my favourite of all is the one I call home: Isla Desirae :) It even makes me smile to say it! It is the prettiest name for a sim I have ever come across and that was just one reason I chose to move my entire beach there from yuckkkky-named Metellus!
I first went there because I liked going to its owner Kim Seifert's live concerts. She's one of the best singers in SL even tho she doesn't sing much anymore. One day she invited me to look around the island and it was amazing! I saw that some parts were up for rental and though it took me awhile to decide (even though Metellus had a horrible name it still felt like home and had lots of memories!), the rest is history!
(that's me when I was thinking about moving!)
There are lots of changes happening on Isla Desirae right now - for instance, lots of horsies just moved in next to me! And a plaza has also been built next door! They are going to have lots of hunts I was told. But my favourite place (except my beach! hehe) is staying the same - that is the middle of the island where there is a park with a Paradise Blanket and tons of SL art that Kimmee has collected. There is also a lovely venue that island residents are allowed to use.
My place is called Harmony Beach. It is the building that looks like a present in the pic up top (it's pink so you probably guessed that already!!) It is on the East side of the island so gets good sunsets and sunrises! I designed and built it all by myself! It's called The Gift of Music and it has a music hall downstairs and a big movie screen upstairs with real cinema seats and popcorn and candy and ice cream and a bar! Next to that I have another patch of land which is empty right now but I usually put themed things in there for the season like in summer I built a Woodstock stage to go there and at Christmas Narnia!
Anyway, for all these reasons, my favourite sim is ISLA DESIRAE! (I also love Here, Livingtree, and Oceanside of course too!!!)