tl;dr: Any suggestion on an Open-Source Software alternative to Grapher / Surfer / Origin / SigmaPlot?
Details: As a scientist I explore and plot data all the time, so I need a quick and easy way to produce graphics. For many times I have been using Grapher, Surfer, SigmaPlot and Origin... all good ones (Grapher is the best by far IMO). But I want to move on to Open Software.
Can you recommend good programs (software) within the open software realm which fits the "plotting" objective? I mean, I don't need it to do statistical analyses or modeling, I just want to plot data. Ideally it should be usable through a GUI with point-and-click (ie graphically-oriented like those mentioned above, not command-line). The result should be an image file (preferably in a vector format).
Also I would like a program which is "popular", ie if I don't understand something I can check forums, etc. rather than find out by myself because I'm one of the 15 users of the program..
Any suggestions? what are the most used and why? have you tried one? I'm looking for opinions/suggestions from users of the Academia/Research world like professors, scientists, students, technicians, etc. who work plotting data from different disciplines.