Use the "advanced" post and attach with the paperclip.
I like the thumbnails because it is cleaner and makes the thread more esthetically pleasing (to me.) YMMV
Yes, my milage varies considerably.
The thumbnails are more cumbersome to view if there are several pictures, and they don't have the same attention getting ability as an imbedded photo. In fact, I rarely open attached photos and move on to another thread...