I swore succulents were boring until I spent 2 hours at the Denver Botanic Gardens cactus house
I always skipped the succulent and cactus wing at the Denver Botanic Gardens because I figured spiky green blobs were all the same. Last Saturday I got stuck there waiting out a rain shower and actually looked at the labels for once. There was a Euphorbia from South Africa that looked exactly like a cactus but is not related to one at all, and that broke my brain a little. A volunteer told me the trick is to look at where the spines come out, and after that I could tell them apart in about 10 minutes. Now I want a windowsill full of them, so what is the one beginner succulent that will not rot on me if I forget it for 2 weeks?
That bit about the Euphorbia looking like a cactus and breaking your brain is so real, same thing happened to me at a plant show last year. A lady there showed me the spine trick too, cactus spines grow out of little pads while euphorbia spines are basically fake and come from the stem, and once you see it you can't unsee it. For a windowsill plant that survives neglect, go with a jade plant or a zebra haworthia, mine have gone a month without water and they just keep on going.