If you were to look purely at the floral business, you would find that roses are the most popular flower bought as gifts for women. This is why roses are so expensive. I actually believe many women only like them because they are so expensive. Kind of a ridiculous cycle, if you ask me.
Obviously flowers are a matter of personal preference, and I have to admit, anytime they arrive as a complete surprise, no matter what they are, it is one of my favorite gifts.
Roses on Valentine's Day are so cliche, that at this point, though I'd appreciate it, it wouldn't mean as much as a carnation or a tulip on a non-holiday.
I like seasonal flowers on my table all the time, and usually cut them out of my yard every other week or so. I love daffodils and tulips on the table in spring. I have a rosebush that grows in a strange and unseen corner of our house, so whenever I see blooms on it, I snip them and bring them inside.
Otherwise, like the previous post says, flower preference is purely a matter of opinion.