Wow, interesting question mr Ultron-5
Definitely the timegem in Cap: TWS as hinted by the name of TA 2, Age
of Ultron. Iīd guess the reason for why Hank Pym is in the mix with his own movie, and not the creator of Ultron, his "greatest" assosciation, has to do something with the fact that Ultron manipulates time to change the course of the timeline hence making it his age. Thatīs all lightyears times infinity away from facts but you asked
Guardians of Galaxy is easier, Adam Warlock is basically the rightful owner of the soulgem. At least in the old comics Iīve read. An example of that is given in The Infinity Gauntlet where Adam can sense Thanos as he has the gauntlet on him.
Reality is probably in the hands of someone connected to all of this, thatīs Thanos or The collector. What did The Collector say in the end of Thor? One might consider Strange for a potential holder of either Soul or reality depending on how theyīll swing his introduction.