Learn ARCgis. Even if you don't master it, knowing the basics of how it functions is great. You can use open source GrassGIS and other platforms to keep up - or you can use the "developer credits" that ESRI gives to essentially get free access to the software (not good for extended research, great for running regressions/analysis for a few projects a year.)
Source: did a thesis using ARC, SO works for ESRI