ATOs are the best available.
They have a GLOBAL Proc ATO that gives free buildups.
They have a Proc ATO that puts them back into Hide, allowing them to 100% crit
Both sets have good bonuses and a nice fat recharge buff
And these both work together.
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Armor sets almost as good as Scrapper, but with much lower threat. While some sets are less good, many are just as good as the scrapper variant. And Stalkers get the same base values as scrappers and brutes, not reduced ones like Sents
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Progressively building crits, crit increase based on team size, etc. Though TBH these are just icing on the cake.
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All the newer primaries have the same AOE potential as scrapper sets.
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So really unless you pick an Older primary with poor AOE, and one of the secondaries that aren't as sturdy, your Stalker is going to play like a Scrapper with more reliable crits and lots and lots of extra buildups.