I think mainly, its just a matter of preference when it comes to brands. Personally I prefer autometer, because its a quality product. Not to mention I think they look better because all the cheap ones I see in stores are black face with chrome or black bezel. Looks disgusting if you ask me.

The gauge pillar you bought from Lotek is indeed a 2 1/16" gauge pillar pod. They dont make a 2". You may need to lightly sand the imperfections around the gauge hole for fitment to be right. Other gauges you may want to look into would be oil temperature, water temperature, exhaust gas temperature, (I dont recommend an air/fuel gauge since they are practically worthless unless you have a wideband), and voltemeter if your just looking to fill a spot.