Don't worry about picking the wrong one. If you enjoy CW and stay with it, you will wind up with a collection of them in short order.
Yup there is a lot of truth in that one!
Everyone likes something different in code keys it seems and many end up with several. I have 5 of them and am always watching for another.
I would just be sure to get one that is in good condition to start with, not something that needs a bunch of cleanup, restoration or has missing parts unless you are sure you are up to it. Keep it affordable, they don't have to be real expensive (when new) to work well for you.
You can start with whatever type, hand key, dual lever iambic, or single lever paddle but a hand key or single lever key I think would be the easiest to learn with when starting out. An iambic key isn't probably all that much more difficult. Historically most probably started with a hand key. I did and went to a single lever paddle at around 15 wpm or so. I primarily use a dual paddle iambic key these days.
The Bencher Steve mentioned is easy to find used and not too expensive when you do.
I would stay away from bugs to get started with.
I would also stay away from the hand key that has the ball bearings in the lever pivots. Too easy to lose a bearing if it gets loose and they are not a great key anyway.
Often at hamfests people have keys hooked up to code oscillators or an electronic keyer so you can play with them a little.
Look around in searches for Morse code keys and get a little more familiar with prices, styles etc.