Uzumaki
Haven't we all, in our own way, eaten the meat of a snail person?
Junji Ito's Uzumaki is the first full manga I've read, and it was an excellent starting point. I like stories about weird towns! I like grotesque body horror! I like eating the meat of snail people!
The first two thirds of the book were my favourite, as increasingly strange, spiral-related goings on start occurring in the small seaside town of Kurouzu-cho. (Wikipedia translates this as "Black Vortex Town", a seriously bad case of geographic nominative determinism.) There's a dreamlike quality to the way events mount to a (usually disgusting) climax, then there's a partial reset as the next chapter begins.
Later, Ito corrals the disparate strands into a proper narrative, and the inventiveness of the early parts slackens, sacrificed to creating momentum. Still, it's a lot of fun, and there is plenty of gross, creepy stuff to enjoy, which, let's face it, is what you're reading it for.