Dropbox all the way. Simply drop files in your public folder. If you overwrite an image you've posted on many forums, it will be be updated everywhere + history. Also good for keeping an easy access to your files between pc's (like game saves for instance)
I personally don't like attachments just because the way my browser handles them. It opens them in the same window and when I click back any post I was working on is gone. It's killed more than a few critiques I've been working on. It's a pain to right click and choose "open in new tab" bahh... if it eats my post I don't…