Considering buying a recent Stern Pro (second-hand, not NIB) and narrowing my options to these two games.

Were they priced identically, it would be Aerosmith, no doubt, if only for the LCD display.
But AS is currently more expensive - by at least $600, probably $1000 (I have not seen that many Kiss FS in France - initial sales were probably very low). As I am not exactly wealthy, this difference is significant to me.

Opinion on game play? I now have a fair number of games on both, but I do not know about long term lastability.
No comment on music please - I am neither allergic nor fan of these groups.
I know about Kiss unfinished code but I am ready to take the gamble - betting a decent final update will come.

Thanks everyone for the feedback - Very useful.

I played AS in the first round of the European Pinball Championship. I was player #1, playing against a better ranked player. he was hoarding his locks and I had to do the same. Ended the game with 5 balls locked without starting MB
He couldn't start it either... and he won by 100,000 points or less !

This is my worry is AS: is it too centered around ToyBox multiball? Are there alternative strategies score-wise?

Decision that may well be dictated by circumstances! I checked but Kiss FS ads are really rare in France. I suspect very few were sold here. I have seen more AS on the market.

Would make sense to buy Kiss first, then wait until AS loses a bit more value to swap.
However, given a relatively limited offer, I am trigger ready for the first that shows up at a decent price...

Not going the NIB route anyway as I simply cannot afford to lose $1000 by opening a box!

I actually did last week end - There is no doubt AS better display is a huge plus, but I would not call Kiss dull.
Aerosmith bias towards Toybox multiball needs to be softened. Every single player I watched - including during the semi-finals - focussed on Toybox multiball. On the other hand, I'd love Gene's head to spit balls in a more reliable fashion... Funny how games released many years ago had more accurate / reproducible devices.