For Australian Conventions, I usually only go if there are several people I know going (usually from here), and that often requires someone significant from Transformers being a guest (like Peter Cullen at Supanova in 2014).
The annoying thing is that you can't take photos of the guests at the autograph area, to remember the occasion or prove that you saw them (not selfies)... which is a big part of the experience for me, to go back over photos to relive/remember the events.
I'd like to go to more, just for the wander around and see things as a "day out", but it isn't as much fun if I go by myself, as having someone else can help fill in the day more if I run out of things that interest me.