Thread is a bit old now so my response may not be relevant any longer and if so, I'll gladly delete.
All of the recommendations I have read so far have been great. Allow me to preface the following by stating I started with the SDB, upgraded to 550, then upgraded to the 650. Along the way, I setup a Hornady LNL AP. Currently, both the 650 and LNL AP are still in production at my place and I'm a huge fan of both of them.
Given that the 550 seemed to be the most recommended, I thought I'd throw another one out there for consideration and it is the Lee Pro 4000. It can be purchased for sub $250 and would include shell plate for one caliber along with appropriate dies for this caliber. It will also ship with a case feeder. It can operate as full progressive or manually indexed like the 550. I had one setup for a while and I actually really enjoyed loading on it. The old Lee priming system woes one reads about often were non-existent on my 4000. While it took just a tad longer to load primers, it made up time in other areas such as large/small primer swaps. It is not built as robust as either the 650 or the LNL AP (a lot of plastics), but it functioned correctly and if a part were to break, they are super inexpensive to replace. It ships with the Auto-drum measure and mine was easy to adjust and consistent with WSF, WST, and Clays.