Remember each of the above have differing grades of fabric – GoreTex is available in many flavour’s from cr*p to good.
In my opinion, cut, fit and ventilation matter more than the fabric. e.g. my own personal jacket is a DT Entrant ‘cheap’ Montane – and it is ace.
The only difference for me is with Paramo – it does last longer, it is warmer, it is quicker when drying out.
FWIW, I had very cheap deals available at work from Mountain Equipment (GoreTex ProShell) and Montane (event), and we bought at higher price 12 new Paramo smocks. They are not perfect, but they are (for us as outdoor instructors, outside day after day, and usually standing around or on water) the best choice.
If Paramo is watching – Adventure smock, cut better (longer body etc), sort the pocket to a simple on the front tunnel, better colours and a matching waterproof short…and I will buy it now 🙂