Have had both a MET and TWD in the house, as well as having LOTS of time on ST & GB
If you want flow it would be ST, MET, GB then TWB
The rules on TWD are not as deep as people make out. Simplifying it a bit drop targets light modes, and 3 of 7 shots kill a walker. Everything else comes from them. It's also an absolute drain monster at times, with the shots you need to make leading to putting the ball out of control, not a great opportunity for combos.
MET has more things around the playfield to aim at which actually contribute significantly to scoring.
ST seems a bit simple to me, start mode, shoot flashing lights, rinse and repeat.
GB is great to play, but not the Pro - Prem is way better - but if that's out of budget I wouldn't bother with the Pro
There's more significant GAMEPLAY differences between the TWD & GB Pro and Prem than the Pro & Prem version of Met & ST, which are more cosmetic.
But with everything considered I'd go Met, then TWD, ST & GB in Pro versions.