I've played all versions and I think there are several Pro versions that basically play equal or even better than their upgrade counter parts. With Prem/LE, many times you are paying multiple thousands of dollars for lights and art differences which are hardly ever worth it to me. IMHO...
GOT pro plays better than the Prem/LE. Upper playfield is a huge waste unfortunately and the upgrades have the left orbit design issue.
TWD pro plays very good, but not having the walker bombs is a game changer. I would upgrade here if the price was right due to those alone.
Tron pro plays just as good as LE, get Eli's ramp mod kit and save yourself $4,000+.
KISS pro plays just as good as Prem/LE. You're paying for a 2 second floating ball trick and a drop target to upgrade.
MET pro plays just as good as Prem/LE. Hammer is cool when it works and the moving snake head and cross are nice, but the Pro is a great complete game.
Star Trek pro plays just as good as Prem/LE. You are paying $2,000-$3,000 for lights to get Prem/LE
Aerosmith Pro plays as good as the Prem/LE, but I have to say I do like the drop target and upper playfield. If the price was close I would upgrade here.
AC/DC Prem/LE plays better than the pro. Drop targets, swinging bell and lower playfield and other additions make it worth it.
X-Men Pro plays better than the LE. Ice Man ramp is a negative, and you don't lose anything not having the spinning disc and pop-ups.
Transformers Pro plays better than the LE. Iron Hide ramp is a total waste, Megatron physical ball lock is hit or miss and moving Starscream is sad when it just drops the ball off the wireform.
Avatar Pro plays just as good as the LE. You are missing a power ball that doubles scoring.
Ghostbusters Pro is a very packed game. I don't miss the physical lock and moving Slimer, but if the price was close I would upgrade.
Wrestlemania Pro plays just as good as the LE. The LE is appealing to me only because of the classic wrestlers vs. current wrestlers.
Mustang Pro plays just as good as the Prem/LE. The huge spinning turntable is a negative for me and I don't miss the pop ups.
Avengers Pro is all there, you are just missing the crossover ramp which I do like. These are so cheap, it would be worth upgrading.
Star Wars Pro plays just as good as the LE. You are only missing out on the hyperloop and it is not worth $2,000-3,000 by any means.