I've owned the Premium/LE DP and IMDN and a Pro JP.
This all comes down to personal taste in my opinion but I'll share mine.
Deadpool - Haven't spent enough time on the Pro, but I really like the lift ramp and extra drop targets on the Prem/LE. The disco ball integration is superior to the mod on the Pro so those are all pluses for me that if I had to make the purchase again I'd take the Prem over the Pro when it comes to DP. I'll take a full set of drops over targets any day of the week... as a plus... I much prefer the cab artwork on the Premium than the Pro.
IMDN - I've put my two cents in on this on Pinside more than once and I stand by it... I like the game to keep moving, I don't like breaks in play while animations and things go off and move around... for this reason... I think if I had to do it again I'd go with the Pro. The sarcophagus is a super cool mech... I love it... and I loved it the first 3 or 4 times I locked a ball in it... now I just wish I could get on with the game every time the ball goes up that ramp... so I'd be fine without it. Same thing with the lift ramp... really cool... but after a while and playing a ton of games, I don't need it. I forget what they call the newton ball target, but whatever, it's neat, once it is dialled in it is fun to hit as opposed to a standard target, but at the end of the day I'd be fine with the Standard target. One negative on the pro for me is the Artwork, I really do prefer that of the Premium.
JP - I've played the premium for a bit and I think the part I missed the most on my pro turned out to be the raptor pen as opposed to the ball eating t-rex. For the same reason as IMDN above, I want the game to keep moving, as it is the Pro used to drive me nuts every time you'd start T-Rex multiple, no way to break the animation and just keep playing... it is an awesome mech, I love it, but I can live without it. The raptor pen on the other hand does give the game a different feel altogether, I'd miss that if I was a premium owner... if I had to make this purchase over again, I'd probably go premium just to put more miles on it and I gave the Pro a pretty good go... so change would be nice.
If you are trying to "justify" the additional cost of the premium it will always be challenging... so if you can spend some time on any of them do so, that is the only way to really tell, YMMV of course.