OP I felt similar to you after finishing Bake, but after finishing the series it's become my favorite franchise purely for the characters.
Monogatari is all about the relationships the MC has with each character (at least before the plot gets crazy like it does later). There is just too much information in Bake to notice everything you need to notice. You miss so much about the characters since you're struggling to keep up with wtf is going on.
Just to expand on some things /u/Seraphaestus mentioned.
Senjougahara basically has asperger's at the moment and you should just treat her like an autistic kid. She's been emotionless for 2 years and now has problems displaying her emotions. Remember in the first episode Araragi mentions that all she does is read? She flat out says I'm a tsundere, and she guesses Oshino is a moe character because of his name. That's how her thought process works at the moment - she can only relate her emotions to things she's been reading about for the past 2 years. There's a lot more to her character that makes her much more interesting (she's one of my favorite anime chars) but hope that addresses why she's all batshit crazy in bake.
Hachikuji however she doesn't like this so she actively tried (literally and metaphorically) to push people she met away. Read the lyrics to her second OP.
Lost but not at a loss
I met you
As you pretend to tease and bother me
I pretend to be a little angry
And savor the mundane joy.
The groping started when she lamented how he was her first touch so he responded with "oh yeah? I'll grope you so hard you won't care about that." It's all just playful banter between the two, nothing sexual. Notice how after Nadeko's arc when Nadeko is thanking him he tries to playfully lift her skirt (he stops before he actually does). She doesn't react though and he stops messing with her after that.
Just like /u/Seraphaestus said, Nadeko is generic on purpose, watch her later arc when she becomes awesome.
Hanekawa is pretty generic on purpose also, except they hint that there's more to it at the end.
Hopefully both our walls of text are enough to atleast convince you that the characters aren't utter trash and you give the rest a shot. Just to warn you though Nisemonogatari is more of a thematic stand alone season compared to the rest. It doesn't focus on the overarching plot aside from introducing important characters so a lot of people consider it filler or don't like it (which is a shame) also the fanservice is in overdrive and it's probably going to be like pulling teeth for you. It's worth it though to get to monogatari second season.