Edit: Warning- Wall of text incoming
TES:Arena- When I first got this, I was used to Skyrim-style open-world bloom ARPG and over-cinematic "RPG"s like Mass Effect. Then I played into this one and actually kinda disliked it at first, but then tried it again about three to four days later and approached it differently, leading to a long lasting love and appreciation for it.
Fallout: New Vegas- At this point, (pre-Arena, during my PS3 days) I had absolutely zero experience with Fallout. I had heard about how amazing Fallout 3 was from a friend, and was bored after putting a metric shit ton of time into Skyrim. So, I took my allowance down to gamestop to get Fallout 3 and couldn't find a single copy. But, sitting there was New Vegas, a game by some shitty side company. I had heard from multiple sources that Fallout 3 was far more worth the 6.99 USD. But, I decided to get it anyway. And I hated it. Eleven year old me could not grasp the concept that I was under leveled for an area and I kept on getting my ass handed to me. I put it down and vowed to hate this Obsidian corporation forever for ruining the PA setting for me. A week later, I was bored and started a new character and heeded the in-game advice to follow the roads south. Now, it is one of my favorite games of all-time.
Fallout- After New Vegas, Fallout in my mind was supposed to be a FPS action-RPG with good story. So, when I saw on Steam after getting my first PC that Fallout was originally isometric, I was reasonably skeptical. But, I took the gamble and spent 20 USD on the collection on Steam. I hated the isometric Fallouts. They just didn't feel right to my fourteen year old mind. They were too hard. I went back to Morrowind and didn't touch them for a while, thinking I had made a mistake in purchasing them. Then, I looked up something to do with New Vegas and landed on the Codex. A thread here, can't remember which one, led me to look at Fallout 1 differently and I tried it later that night and fell in love. Now, over the past year, I've played Fallout 1 all the way through more than three times.
That's all I can think of right now.