RPGM is my preferred engine.
In somehow makes feel you in control of the character, something that Renpy doesn't offer and a simple "powerpoint slide".
RPGM you can navigate around and "own" the character.
Unfortunately the devs completely ignore best-practice of RPGM. I remember a game I really loved LIDA's Adventure.. but it was a serious pain playing.
Road Trip I love it, it is like Elena, simple story, leverage on lack of money and documents.. just nice.
In terns of eroticism.. at the moment I like LISA, it is not my taste the vanilla ice cream.. but my god.. the sex scenes all well represented with a lot of images and not the classic checkbox exercise.. those scenes last long enough to raise my heart beat.
The one in my heart is now Fashion Business, but I appreciate there is a little bit of fatigue from the Dev after 4 long chapters.