There seems to be just 2 companies out there with left hand AR's-Stag Arms & Rock River Arms. This is my 1st venture into an AR style rifle, and looking at the 223. Does anyone have positive/negative insight on either of these rifles?

I have a left handed STAG that goes bang every time that I pull the trigger, no complaints at all. A lefty upper isn't really necessary if you have the case deflector on a right hand one but I enjoy mine.

Have two Stag uppers/rifles. Like them both. Having the LH option is great IMO. Go for one!

I have handled a LH Stag and if I buy another AR, thats what it will be. I have built two AR's using Rock River components and they were great. I have also owned a Colt H Bar and a QPC shorty. They were great as well. All of mine were RH and I had no problems shooting them as a lefty.

Actually, as a left hander, I like shooting the convenetional AR's (right hand) instead because I can tell immediately the nature of a jam or malfuction because the port is on the right side.

I agree with sbsmith about ARs. A LH AR is a solution to a nonexistent problem. Also, I have a LH Benelli SBE auto shotgun and I find that I use my RH Benelli M2 more because the oprod handle is very convenient for operating and clearing the action.

I'm with sbsmith. I like shooting a standard AR left handed.

Some companies are producing ambidextrous operating buttons which will make operating them fairly neutral.
It depends on your chosen stock, physical dimensions and sighting equipment the forward assist can be in the way of a left handed shooter.
The only noticeable difference is the ejection of the spent cases will be in direct line of your line of vision. While the left eye is sighting, your right eye is locating targets. You have to see what works for you.
I personally appreciate all companies that take the effort to manufacture lefty's and prefer left hand rifles when available.

I like the safety of a LH rifle shooting it LH, not a problem till a case blows or you have an incident.