Meant to reply to this earlier, but I forgot
Genji is fun, but I'm awful with him (and in general tbh), so I usually end up dying a ton and not doing much. He was pretty ridiculous before the nerfs because he had a super easy ~170 damage combo grâce à animation cancels, and his ult lasted like 20 years. It's too bad you weren't around for the Summer Games because Nihon is his best skin ATM. Sparrow is an acceptable substitute, though.
Sombra is one of the coolest character personality-wise and lore-wise imo, but she's so bad. Basically everything she does, another character does better. The unique things she has (ult, hacking) aren't even good enough to set her apart. Like, hacking an enemy takes too long and is too easy to interrupt, hacking healthpacks doesn't really matter when the enemy has competent healers and her ult is extremely reliant on team coordination (which isn't a bad thing, but the ult itself doesn't have enough of an impact to help her case). She's supposed to be the answer to Reinhardt and hiding behind shields, but she's not really that good at countering that. I also like playing her a lot, but she needs buffs to be relevant. Virus and peppermint are her best skins btw.
Zenyatta is cool. He's not "meta" anymore after Discord Orb was nerfed and Ana got buffed, but he's still useable. His personal HPS is kinda trash, but it's good in combination with another healer. His DPS and ult are his main attraction tbh. Nutcracker is amazing, but ascendant, Ra, and harmonious are also cool.
Have you tried out Ana? She's completely reliant on your ability to aim (more so than most other characters), but she's really rewarding to get good with. I think she's the most fun character in the game, but healer is my favorite role, so I get if that's not your thing. Turquoise is her best skin imo.
I didn't intend for this to become a huge wall of text, but whatever. I hope you're enjoying the game so far because it's one of my favorites.