I use :) :( :D <3 </3 :p :o XD and 8D regularly, and occasionally things like :x .-. and :s. I also enjoy using the Trozei sprites on PC since they can make any post seem more tacky fun. I don't often use the image versions of smilies though since they don't often construe the implications of the text very well, so I tend to stick to the plain text versions.
I use them all of the time. The most common ones for me are O_O, O_o and XD. I'm serious. Oh and I also like using :3. There's a lot of them I use, but i can't name them all... I think the ones I mentioned are more common for me.
Other times I use >o>, >w<, ^w^, O w O... among others. lol like I said, I can't name them all. I think my favorite one out of all them is >w< Because it's so cute and adorable.
Oh and I also use TT^TT, TT_TT, TTwTT... and yeah. I'm pretty much naming them as I go along. XD My most commonly used smiley though is XD.