I'm always very wary of selective memory when thinking about characters throughout seasons.
Because my usual sentiment is that S1 Pinkie was the best - with her cute short jingles and songs on random occasions, some of that higher awareness/4th wall craziness (Swarm of the Century, FPK, and a lot of the random bits throughout episodes), especially compared to later seasons where she starts filling the comic relief role more often, when the episode is not focused on her, and it's like the social intelligence is gone (never forget Filli Vanilli).
But then I remember that Pinkie was also pretty shitty to people in the Smile song episode, Over a Barrel, and possibly others. And then I'm not sure that my judgment is sound or fair anymore. I want to say she was better in S1, but it's a gut feeling wrapped in headcanons and opinions I read on the internet, and I don't have the energy to actually go through the 150+ episodes to make an accurate assessment.
Rarity at least seems to be more consistent. She didn't have any major character boners, and I think that comes with Rarity being the more mature one with a dramatic side, while Pinkie is a ball of randomness, so you can't really say what the norm for her is and when it's crossing the line.
There are still things that can be questioned - like the whole AJ as a judge decision in Honest Apple (and letting it escalate), the entire PPOV episode, the deal in Spice Up Your Life, etc.
Basically what I'm saying is that both rarijack and raripie are bottom tier pairings.