[TimeAZ]

Both are great and are very classic of the brand. Hard to pick one over the other for an entry into Omega. I wound up picking the 300m.

My opinion of the pros/cons for each:

SMP 300m:
+ Awesome movement. Self-winding.
+ More water resistant. Designed for diving.
+ Tasteful integration of date window
+ Ceramic finishing, premium feel
+ Better legibility in my opinion. Dial is less crowded.
+ Factory rubber strap is incredibly comfortable and well made
- Metal bracelet is very uncomfortable. You HAVE to get the rubber strap for this.
- Less dynamic watch for strap changes. It has to stay on the rubber.
- Less dynamic watch for day-to-day wear. Too sporty. I find that it is not dressy.


Speedmaster:
+ More history. Classic, timeless, enthusiast level horology.
+ Offers chrono complication, if that's your thing.
+ Greater day-to-day wear, in my opinion
+ Strap monster. Looks great on leather, NATO, etc. More dynamic.
+ More comfortable metal bracelet. Can add micro-adjusting clasp via aftermarket.
- Dial is crowded, time can be harder to read
- Movement is manual wind and less magnet-resistant (most versions; some self-winders out there)
- Not sure how robust or accurate the movement is; lacks the METAS master chronometer certification
- Do not take this watch in or near water. Only 50m resistant.