In general terms, E71T-1M must be about the easiest and most forgiving electrode ever built. It has great operator appeal. It tends to operate over a wide wire speed range, and for a given wire speed the workable voltage and stickout is relatively broad.
The slag comes off easy and the electrode is not prone to undercut. Works great in all positions and on pipe.
It is not prone to internal discontinuities unless the welder is doing something substantially wrong. The only common mistake I see low skilled guys prone to making with this wire is the same problem you see low skilled guys making with other wires - trying to hog in a fatty, and then experiencing slag inclusions or lack of fusion.
Only downsides I can come up with is it generates a lot of smoke, and for skilled welders it can get quite boring rather quickly. Since it is so forgiving, it just isn't a very challenging electrode to weld. That aside, if I am going to fabricate something from steel in the shop, I am going to use E71T-1M unless there is a good reason to be using something else. It is just so fast and easy to produce good looking sound welds. It gets the job done right and quick.
Personally I like ESAB 710X-M. Made in Hanover, PA, USA.
BTW I would stick to the M for out of position work. Some places go with E71T-1 and cheaper CO2 gas. In my experience if you do a lot of vertical and especially overhead, you are ahead to pop for the -M and mixed gas so the welders spend their time welding and not digging spatter out of the their gun nozzles.