Horror in the Museum is also one of my favs...
With The Shadow over Innsmouth, The Haunter of the Dark.
If you wanna try other books made by the friends of Lovecraft, Zothique by Clark Ashton Smith is GREAT, and you can try The Horror from the Hills by Frank Belknap Long too (The Cthulhu Mythos, or as I like to call it, The Necronomicon Cycle is not limited to Lovecrafts works, its "shared fiction" with his friends and Circle! But DONT see August Derleth or other authors that apperaed after Lovecrafts death, bc they only kill the cosmic horror vibe and put "good vs evil" slop that destroys the whole "We are insignificant" thing... Derleth also introduced a werid "elemental classification" like in Pokemon 🤣 and some gods that care for Humanity called the "Elder Gods" so... yeah, read the Lovecraft Circle and STAY AWAY from Derleth or anyone that introduces the "good vs evil" thingy.

Oh! My favourites are The Dream-Quest of Unknown Kadath, At the Mountains of Madness, Dreams in the Witch House and The Dunwich Horror!