The freedom league has an extensive feeder system - the 'standard' route throughout much of all of those regions is to go contact your local branch, and get a metahuman career councillors. They're also basic staging points, and form a sort of network of reservist support in case of supervillain attacks.They also offer referrals to the actual super hero work - which is pretty intentionally separated out. There system is generally widely praised, though it's noted as generally being a bit slow and very purposefully designed to be insulate the time of the strongest heroes. They do their best work in talking people out of superheroing, and tend to have a bit of a one-sized fits all approach.
The league also seems somewhat intertwined with some of the legal safeguards - metahumans are expected to get tested, though the results of such testing is treated in the highest confidence, even in the case of later villainy, due to backlash after the Cleveland Incident and other, smaller affairs.
Metahuman powers are occasionally regulated as weapons, and the fruits of them are often tariffed or regulated due to the monopoly power that a powerful metahuman can bring to an industry. The US appears to have some hotly contested metahuman draft system in place designed for extreme emergencies, 'such as alien incursion, dimensional catastrophe or other acts of god'.
A number of other teams exist - mostly ones bound together by insurance arrangements and power synergies that make them effective squadrons, using varying levels of emergency powers granted through a certification process.
The Lionhearts are the most prominent british super team, with a focus on dealing with superpowered intrigue, though they also have plenty of heavy hitters. They tend to work to operationalize powers more directly and put their assets to work aggressively - they tend to be reviewed as more fulfilling to work with, with looser obligations fitting with Mutant Maladaptation Syndrome cases. They also tend to prefer boundless-type assets, and tend to be an awkward place to work for those who can't adapt or pick up skills quickly. They're also generally fairly patriotic - and have their own murky history with discrimination.
The Saviours are the most prominent canadian organization. It was built on the back of Miss Mobility's powers, and focuses most on deploying across the country to areas in need of further assistance. While not quite as solid in terms of support of gaining contacts or getting training and power development, they're noted as being especially good at getting people into places of leadership and making everyone feel important.
For historical reasons, there's no real 'main' team to join in the United States outside of the freedom league and the 'freedom knights' - a secondary circle of superheroes who can operate under what is essential a 'franchise' of the main freedom league's team, with limited resource sharing and networking commitments. The experience of the contracted organization varies from place to place and organization to organization.