I would steer clear of the Istick 50. I had one, and it was the worst mod I've had since I started vaping 1.5 years ago. The screws kept coming loose and it even starting firing on it's own randomly. I put it on the charger one night, and I woke up to a strong buring smell. It fired on it's own so many times, it set the cotton ablaze on my Mutation X v4 and melted the mouth piece. I had it fire randomly in my pocket when I was meeting my girlfriends mom for the first time. I ran out of the house smoking like a chimney.
I've had a real good experience with the MVP 3.0 pro. I've put this thing through so much abuse and it keeps functioning like the day I bought it. It's nice that it has a built in cord that can charge other devices as well. Should you chose to change your device again or quit vaping, it can still serve as a powerbank so your money spent isn't completely lost. It has helped me a few times when my cell phone ran out of power. It usually lasts two days of heavy vaping between charges. For me, the 60 watts max is more than enough power.
I picked mine up for $45 shipped at Vapordna with coupon code VTRz7Zws5k ($10 off)
