Hi JH Dees,
Well of course you are right that the Metropolis would give you an increase of the play-ability of your rack, no doubt about that but it consumes quite some HP, so you should ask yourself if that's worth it (the HP usage).
Nice ADSR? Well perhaps not nice to see it but just simple and straight forward to use it is a Doepfer A-140, for the classic ADSR work and easy on your wallet. Personally, my nicest ADSR at the moment is the Erica Synths - Black VC EG (and I got the extension Black VC EG as well). I love to use this EG, not sure if it's still available though... might be not.
An AD I am also very impressed and happy with is the Triple AD from Hikari. Nice & good module and the good news is it's only 8 HP; it uses LED-sliders. And if you don't mind the HP but I guess you do :-) The MOD1 from Waldorf, I am quite happy with it too. Don't buy a Waldorf if you straight away want to get started. I did that with one of the Waldorf modules (I think it was the NW1) and perhaps it was just me, but without properly reading the manual a Waldorf might not be your thing. But I took the time and patience to go through the entire manual once I got the time for it and then Waldorf modules are actually quite enjoyable and offer many possibilities; so does the MOD1.
Sorry, I don't have experiences yet with the Stages.
I wish you good luck on looking for a suitable EG and kind regards, Garfield.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads