I own both.
I have my vote towards MET.
As others have stated the current code on ST gets old fast. All of the level 1 modes are repetitive and seem exactly the same besides call outs and audio. Im content to play a game or two and walk away. Ive contemplated putting my STLE up for sale, but i know from talking to Steve there is still much to come for ST. He knows the code needs work and he's working on it now along with his next project. So I'm holding out hope on STLE.
On the other hand you have MET, i havent enjoyed an adrenal rush game like this since Iron Man. While i may play 2 games of STLE, ill play 10 games of my Metpro. There is lots to do on MET, and the latest code has made this game bad ass. Love the mini wizard Crank it up modes.