I should have thrown some kudos to @Croax for this thread previously. They did a great job.
Providing high level guidance with enough depth to guide a player is no easy task. (data and formulas not required)
My thoughts:
This AT can exaggerate elements which are present in the rest of the game. Stalkers can really leverage play style and primary/secondary combinations.
With a little input 'S' tier as described can become more clear.. An AoE focused Stalker could be a good example.
The only place I'd strongly deviate is on the Regen ranking (of course). It's not really that bad.
My opinion:
It may be a disservice to folks to rank Regeneration so low. It is a very popular power set. But I also get why it is where it is.
For new folks leveling through playing, it may be middle of the pack. For my play style; it is top 3 or 4 while being more engaging than other top sets that lean more set-it-and-forget-it. I and others like some situational awareness requirements. Your mileage may vary.
Regeneration notes:
It is a bit clicky. For many players this can be different and/or feel suboptimal. Clicks can cut into attack chains and some folks simply can't stand that. There is a learning curve to minimizing the impact and maximizing the benefits.
Also if someone is selecting a primary with especially long activations, this can be a tough pairing. Clicks and long activations could have big downsides.
The inverse is also troo, where Regen has an outsized upside if a player chooses to embrace it for what it is and leverage that which makes it different.
Resistance can be very similar to regeneration (this is the only hint I'll provide here).