I do both. I've crocheted for years (since I was about 14 or so and I'm 44 now... gramma taught me) but only 're-learned' to knit last year after my Mom tried to teach me when I was about the same age as I started crocheting. The trouble was that my Mom was left handed and I'm right handed so it was hard for me to figure out from her instructions.
I gave up on knitting for a long time. Since my Mom had passed on, she left me her small stash of yarn and her knitting supplies, last year, I picked up her needles and decided that I was going to 're-learn' how to knit.
I mostly make afghans and slippers with crochet but I'm doing much more with knitting. I've started my first top down raglan (almost done with the sleeve increases), I've made some tube socks and I'm just starting my first pair of real toe up socks
I'm really happy about starting real socks...
Honestly, I really do like both crafts equally. Knitting is great for wearables that don't weight a ton since the fabric is thinner while crocheting is quicker and better for large things like afghans (gotta love granny squares...).
But, my first love is crochet since I've been doing it for so long. Granny squares was the first thing that I learned and it's still my favorite thing to do (well, squares in general...).
And I agree with Nichan, that I have to think a lot more when I knit. To me, crocheting is so much easier, the pattern is easier to keep track of. When I knit, I have to keep counting to make sure that I'm in the right place. When I'm crocheting, I can just look at what I've done and know whether I'm off or not.
One example of the difference for me is... making a shawl. I made the Seraphina shawl in less than a week, working a few hours a day on it. For a simple triangular shawl, garter stitch, it took me well over a month. I'm DEFinitely not a speed knitter