For my i know their is some afflixes that have a spell inside the simulation.
But if you do a simulation their pretty mutch no differencies between them.
Teeming : https://www.askmrrobot.com/wow/simulator/report/26536aadf9b9416cba51be6319f64e4e
Bolstering : https://www.askmrrobot.com/wow/simulator/report/04b240142c214e2d925d2ba9e5b6ffec
Tyrannical : https://www.askmrrobot.com/wow/simulator/report/7648cce981cb4b3ea51c91803ba1c6c1
Fortified : https://www.askmrrobot.com/wow/simulator/report/002f9fba7ff74d21a72d378d174253ab
Because MM+ script and rotation does not change mutch te result may not change as mutch.
Compare to Legion, you will often go out of mana. Two trinket mana may provide more healing than staying oom more often.
Also, their is a report i’ve looked into were is darkmoon card mana trinket is ranked too hight and provide less mana on live serveur compare to AMR.
Personnaly, i prefer have a passif healing trinket and one mana trinket.
For the last part:
AMR gearing strategies are done using all combinaison of talent / trinket / proc / passif you could have and will be more complete compare to one custom strat you could do yourself.
If you want to do a custom gearing strat it’s for a specific combinaison of talent / boss script / length of boss (it can have an impact very important on stats).
I suggest you to stay with AMr gearing strat and if you want to perform better, may be change your gameplay a bit. Using Weak auras to get the information you need when you need it (for exemple anticipation for healing is really important or understand how the fight work).