Debate begins now!!!
It has already been discussed multiple times Here, Here, and Here.
I prefer ROBOTC (even though some of the PROS features are REALLY nice).
I am saying RobotC. Simply because I have an uninformed opinion and have never used EasyC. 
To me though they seem like two ways to skin the same cat. (please note: I do not advocate for violence towards animals).
I like skinning cats. 
Easy C is simple and fast to program with little experience.
Robot C is a bit more difficult for a noob like me to program with. Robot C however is much more versatile in my opinion. It also has real world applications. And I really love the super fast download speed.
All in all. As discussed before, I believe robotC is superior to EasyC. I have no idea how the other programing languages/ programs are in comparison.
Free software > 30 day free trial > 7 day free trial
Therefore, PROS > RobotC > EasyC
Call me a cheapskate, but that’s how I see it. I switched from RobotC to PROS when my free trial ran out.
Ah, but.
Open Source software > Free software > 30 day free trial > 7 day free trial
+1 - 
My team has used EasyC for many years, and I have to say, there are so many things you cannot do, or at least difficult to do. For example, currently we are unable to upgrade firmware to 4.0.1 and whenever we upgrade by turning off the verify systems we have motor delays. Meaning that if the left joystick goes up, the motors delay 1-2 seconds then turn left. That is why we are switching to RobotC next year. I recommend using RobotC for any team new or experienced because of the many capabilities that you can do.
I used easy c this season and had no problems with the new firmware.
That being said I am planning on making the switch to prose just so I can learn about classes and stuff like that.