controller is one of the simplest agents to play. and they can typically blow their smokes and run in with duelists, which is good if you're an entry-IGL type.
initiator used to be a good IGL role when sova was always played, since sova is kinda designed to sit back and stay alive all round. fade/skye/kayo are all used as entry agents NOW though, so controllers are still >>>
sentinel agents are decent for IGL, but you're lurking on attack and not with the team, so it's not ideal. i threw them in since FNS