As stated before, 74 operators in total are present in both attack and defence. Each operator has unique abilites, weapons, and gadgets. You cannot pick and choose weapons on your operators, they have been selected already, but you can't take all of them. Gadgets like grenades and barbed wire also have this rule applied. They also have different speeds and health. An operator can have the following:
One speed, Three Health
Two Speed, Two Health
Three Speed, One Health
Each operator has a set speed and health, but future updates may change this. Personally, having a balanced health and speed is best. (e.g 2 speed 2 health) You can take more damage, whilst being able to freely move.
All operators can have an impact towards the game, from giving your teammates extra aid, to denying enemy entry or their abilites. I will list a few of the most picked/banned operators, with a personal ranking on them.
S Tier Attackers
Ace
Ace is one of the best attackers in the game, his ability is useful for pretty much every single site, and his loadout is deadly. He has:
S.E.L.M.A Charges that are thrown on reinforced walls to open them
One of the best weapons as a primary (AK-12)
2 Speed 2 Health
Dokkaebi
Dokkaebi is another amazing operator, her loadout and ability can change the game:
Hack defender phones twice to call them, letting attackers pinpoint their location
A great DMR and BOSG slug shotgun as a primary, both are perfect choices for long range
SMG 12 as a secondary, which is the best SMG in the game
If a defender is killed, she can hack their phones, letting attackers use defender cameras
Twitch
Twitch is my personal favorite operator in the game, whilst some people may argue she is A Tier. Most people agree she is an S Tier operator:
Two extra drones that fires lasers silently to destroy enemy gadgets, recharges overtime
Her weapon has some of the fastest TTK in the game, with the high price of some of the most recoil. It's my personal favorite weapon
Very easy to unlock, either buying it for 10% of the normal price of all operators or through challanges
Ash
Ash is favored in the community, her agile playstyle makes her a loved character:
Her breaching round can quickly destroy barricades and soft walls
Her primary has been titled the greatest gun in the game, being the R4-C
3 Speed, 1 Health
S Tier Defenders
Mute
Mute is my personal favorite defender, he is also considered the best defender in the game
His 4 mute jammers disrupt any technology, like drone or hard breaches
He has the best shotgun for a primary and the SMG 11 as a secondary
He has a nitro cell, one of the best defender utility
Doc
Doc is a very valuable ally to have, he is the best operator for support
He has a pistol with three stims, able to fully heal and revive teammates and himself
His MP5 is one of the best defender primarys in the game, with low recoil and a great firerate
He has a special revolver, that shoots shotgun shells, which is good for creating rotations in soft walls
Mira
Mira is great for putting pressure on attackers, infact she currently is the most banned defender in ranked playlists
Her vector smg has some of the fastest TTK, with low recoil
Her ability is two one way bulletproof windows, making attackers think before they push a site
Mira also has a nitro cell, perfect for her ability
Bandit
Bandit is important for denying breaches with his ability
He contains 4 car battries to electrify metal utilites, espically reinforced walls
His MP7 is deadly for headshots, great gun overall
Bandit also has a nitro cell, it's oneshots anything