I don't profess to be an expert but I keep a nail file in my glovebox just so I can always be ready to finger when the opportunity presents itself lmao. That being said, my favourite place to play, after getting clit and g-spot properly lubricated and activated, is the A-spot. Running fingers up from the g-spot, following the smooth anterior wall, you can sometimes hook the tips in the little space at the top, the alcove formed between the wall and her cervix. Rubbing my fingers in that spot gently, less 'g-spot come hither' and more like going up a little kicker ramp with your fingertips, produces some of the most exciting reactions IMO.
I'll leave it to the true vagina-havers to explain but I've been told it's a different kind of pressure and sensation that I find a lot of women don't explore often that has resulted in some phenomenal, sometimes animalistic, orgasms, including some first-time squirters. Easier to reach in petite girls but if we can get the tip of my dick in there while fucking, usually in cowgirl, for me it's the best.
It's not for everyone, I imagine, but like
@LeDodo, I just got aroused typing that out.
editors note: I wrote a whole fucking page about this and trimmed it down before posting because it had become a story on literotica or something lol.