If you like Orianna, definitely Lulu. Lulu and Orianna have very similar kits albeit set up a little differently. They both have magic damage AA buff passives, they both have a shield, they both have a slow, they both have a speed up, both of their ults are AoE knockups. Orianna has more damage and Lulu has more utility, but there is definitely a lot of comfort in Lulu if you enjoy Orianna. At least that's what I believe from personal experience. I used to love Ori when I was leveling up and fell in love with Lulu sometime after hitting 30.
Lissandra is also really fun but she's a bit different than the other champions you consider yourself comfortable on.