Personally, I think Kelly was the nicest.
So my rank would go like this:
1. Kelly
2. Kris
But I would say that Sabrina, Jill, and Tiffany are about a tie.
With Julie being last (or the least nicest).
1-Kelly
2- Kris/Julie
3- Jill
4- Tiffany
5- Sabrina
Julie was humble, always happy and enthusiastic all the time, so it's a tie with fun and smiling Kris.
Kris became kind of bitchy when she was fighting with Kelly over Patrick Duffy in the "One Love, Two Angels" episode.
Guest star Jill was often rather snobbish and stand offish.
Season 3 Sabrina behaved a little condescending at times.
I would say overall, Kelly and Tiffany were the nicest. Also, Julie ( when she wasn't hypnotized lol).
Tiffany was the sweetest Angel.
Kelly was the most maternal Angel.
Jill was the friendliest Angel.
Julie was the most unpretentious Angel.
Sabrina was actually the kindest, warmest Angel.
Kris was the spunkiest.
"Yes, tubing, my precious one! Haven' t you ever tubed?!" - Ida