Edraw Max is a professional technical drawing software that I used to draw my architecture diagrams. It is very user-friendly. It has a lot of symbols that can be used for network diagrams, floor plans, maps, business charts, organizational charts, mind map, workflow diagrams etc. There are also templates given for our guidance. This software is like Microsoft Visio, but has more symbols and pictures then Visio.
Overall, my experience with Edraw has been very good. I recommend this software for all the research students who wish to put their ideas into diagrams for their publications and presentations.
You can download the trial version or buy Edraw Max from here.