I've used Blogger, WP, LJ and DreamWidth in my time. I wouldn't really recommend either LJ or DW for anything but a personal journal (albeit a sociable sort of one), and DW over LJ, definitely. LJ's going up the creek lately.
Out of Blogger and WP, I prefer Blogger. I actually switched over from WP to Blogger because I got sick of how restrictive the free WP accounts were -- you can't change fonts or put things where you want and so on, whereas with Blogger you can pretty much do what you like. You can also set it to link to your G+ profile if you like, if you have one, which adds another social aspect and helps build up a readership. But as others have said, in the end it's personal choice...