I recently played around with Stamina builds on every character in BNW after I discovered that everybody has at least 1 Stamina boosting esper, and I had some ideas for improving Stamina-based builds that I'd like to throw out here.
First off, I think the most recent patch making Counter and Cover go off Stamina to determine their proc rate is absolutely genius, and C/C builds have been some of my favorites since then and I love having a useful purpose for Stamina other than just being a third "damage stat" for niche builds.
I think there should be an event in the WoR that becomes accessible once you have Relm and Shadow (and maybe Strago) that switches Interceptor over to Relm. My logic is that Shadow can easily get sky-high physical evasion and that between that and Image-spam he should almost never be getting hit, and therefore never proccing Interceptor, while Relm otoh still gets hit plenty and could really use an extra use for her Stamina since she has access to a +2 Stamina esper. Alternatively, being able to trigger an event to switch Interceptor back and forth between them could work too, or maybe even a Relm-exclusive relic that let's her use Interceptor.
On the subject of Relm, if her paintbrushes healed with Stamina that could give it some extra utility too; with stam-heals, regen-x, interceptor, and Stamina-based sketches I think Stam Relm could finally become a widely used build.
Strago, Edgar, and Sabin all come really close of having good Stamina builds imo but just fall short of where they should be. Sabin's main shortcoming in this department is that his Stam build would need both relic slots for covering and countering, and with his low defense I don't think this makes him very appealing as a tank, so maybe a unique piece of equipment that gives cover or counter to him? I kind of like the idea of claws having inherent counter, making him more like the monk from FF5, but since all of his claws are elemental that would probably be awful in practice, since he'd counter enemies with elements that they negate/absorb all the time. Edgar's Stam build is nearly great, being really beefy and still being a great status setter, even if he loses out on damage, but his low starting Stamina and poor damage options outside of the Omega Weapon hinder him here I think. It'd be good if he started with 30 or 36 Stamina instead of 24, which would not only make him cover and counter more but also let him invest some into another esper on his tank build to give it some more side benefits rather than demanding every EL be invested into Unicorn to make up for his low Stamina, and/or the Gungnir getting its "strong vs floating enemies" property back, giving him stronger counter-attacks. Since that property wouldn't proc on jumps it would also make it more solid in its role as a "tank weapon" instead of a "damage-dealer weapon". Then there's Strago, whom I really want to have a great stamina build, but I just don't think rod counters on such a flimsy character and a strong Odin summon are enough. I'm not sure what to recommend to buff it on Strago though, maybe have it somehow make Holy Wind or Raid stronger?
Mog's Stam build is pretty good I think, I like having a sturdy tank that'll counter with rod spell-crits, but I think it'd be even better if he could dance and C/C at the same time, which would allow him to use one of his dances with a lot of Stamina-based healing while still covering and countering, otherwise he needs the Moogle Charm if he wants to dance AND cover, which locks him out of countering. I think losing the ability to control his dancing in exchange for the ability to counter would be a fair trade-off and would effectively give you two major ways to play Stamina Mog. Besides, its a shame he can't really use his dances on a C/C build as of now since there's synergy with his high Stamina on it.
On pretty much everyone else, I've found their Stamina builds to be pretty solid (esp. Terra and Cyan), so it's really just those five that I think need to be improved upon a little (or a lot in Relm's case).
Does anyone else have any ideas? I like the idea of Stamina being less niche and would love to see it have a stronger place in any future patches.