If i may be so bold as to imply that "G2" could be the worst selling line?
This is coming from a dude who was there in front of the T.V in 84 watching the original series air at the ripe age of 6 years old. Be present to witness and experience the global phenomenon called Transformers take the world by storm and carry out too become a feature length major motion picture two years later. Than continue to stick around till around 88 or so but by then had split the "scene" to pursue other interests. Kids do have a short attention span.
Then puberty had begun to take control and I had switched gears to join in the hot pursuit of sex,drugs and rock'n'roll.
With that being said and in the context of my personal experience. I had lost ALL interest in the franchise till Beast Wars arrived in the mid 90's. It had resurrected a forgotten childhood passion with an unexpected reboot of the TF concept but with a competent story line that was worth tuning into bi-weekly and was worthy of respect.
But i reckon that dark period from 88 or so till Beast Wars had come along is the time that most folks(target market i.e children) had lost interest and had succumbed to those throbbing biological urges brought on by puberty and had left the franchise in the "dark ages" (that i surmise) known as G2.
So in conclusion. I hypothesize that G2 is the worst selling line.