In your OP, you indicate an intention to go to the Instructor level, but also make reference to the opportunities available BEFORE the Instructor level. In the SSI system, it appears (from the SSI website) that Dive Cons can teach the Try Scuba Diving (pool) course, whereas, in the PADI system, a DM cannot independently teach Discover Scuba Diving. Rather, an AI level of certification is required. A small difference, but it may be important to your particular direction.
Ultimately, if what you want to do is teach Open Water Scuba courses, and beyond, then the goal should be Instructor-level credentials, and the small agency-specific differences in entry-level professional opportunities are not that important.
SSI's Dive Control Specialist level is a combination of Dive Master & Assitant Instructor. Dive Cons Can conduct "Try Scuba" sessions in the pool, do skills updates for divers who've been out of the water for a while & can teach snorkeling & a few select specialties.
Where PADI Dive Masters & Instructors can teach independently of a dives shop or resort, SSI Dive Cons & Instructors must be affilated with a Dive shop or resort.
There are plusses & munises with either way.