Modkit: is pretty much dead, VEXcode IQ blocks has all the features of modkit with fewer weird bugs and quirks.
ROBOTC graphical: has mostly been replaced by VEXcode blocks for new users as well, but some teams may be sticking with it because they’re already familiar with it.
ROBOTC text: has not yet been replaced by VEXcode (VEXcode IQ text is due out in April/May). Probably most IQ teams doing text-based programming will be using ROBOTC to do it.
There is also RobotMesh Studio, a browser-based programming solution for IQ and EDR with support for graphical programming in Blockly and text-based programming in several languages. RMS has lots of really cool and useful features but a couple of caveats worth noting:
An internet connection is required to compile and download code. Most tournaments, including Worlds, do not provide teams with an internet connection.
There is an offline app, but it only runs on Windows and may not receive updates quite as quickly as the browser version.
If your team has no previous programming experience, you should probably start with a graphical solution (such as VEXcode blocks or RMS blockly) and work your way up to text-based programming over time.