I think @SergeantQueen‘s advice is spot on.
Personally, I found crochet easier for years. I was so prone to dropping stitches in knitting and it was beyond frustrating to have to backtrack and fix it. I also used a slower technique to feed yarn the beginning for knitting, which was a drag.
As I got better at knitting, I found my crochet knowledge to be quite useful—a crochet hook is a great tool for fishing a dropped stitch back up the rows, for example. I also use a crochet hook for casting off. And when I switched knitting styles to something more like the way I fed yarn in crochet, maintaining consistent tension became easier.
So, from my own experiences, starting with crochet first was better—I found it less frustrating initially, and I found that most of my crochet knowledge helped my knitting when I finally got to it. Of course, I can’t speak to learning knitting first and then crochet.
Crochet is easier to work in different shapes—the crochet hook can turn pretty much wherever it wants to go, and you don’t have to worry about leaving open stitches behind. I also think it’s better for lace, but that may be a personal preference. Each stitch in crochet is essentially an intricate slip knot, so crochet is good at holding a particular form. Once you make a stitch, it’s set.
Knitting has more elasticity to it. The stitches are more interconnected—loose loops instead of the slip knots of crochet—so they give and take from each other. This makes it probably the better choice for things like gloves, socks, and most sweaters. (Which is actually what convinced me to finally learn it.)
As for versatility—the more you delve into either craft, the more you’ll find that people have found ways for each to do pretty much anything the other does. But some things might be simpler to do in one than the other, or the type of fabric resulting from one or the other may be better suited for a certain project.
If you know you want to learn both, I recommend something like an overhand grip for the crochet hook (it’s titled knife grip on that site). It’s closer to the grip you’ll have on a knitting needle, and you just roll the crochet hook slightly in between your fingers to change its orientation. And at some point I’d recommend learning continental style for knitting, even if you start with English. In continental, you feed yarn more like you would in crochet—so, once you get the tension down with that feed, you don’t have to alter much between crochet and knitting. (But if these grips don’t work for, of course just experiment and find what you like.)