T2 beats any other type of guns by a simple fact: best performance for the price it costs. Yes, you can find better stats, way more expensive. Yes, you can get similar stats for cents, but you will always be wanting better stats.
When you come up with a brand new fit, the first thing you do is to test its values using T2 guns, if you like it, then you upgrade to faction / officer than can actually perform better, or have reduced fitting which allows you to get a better setup; but T2 is the base for calculation you use because they are like the simplest best gun you can get from the market at a good price, without sacrificing some stats to T1 versions that will always have some downside even if they have all the same attributes.