This comparison seems to me very unbalanced, I do not say it by popularity but by the so abysmal amount of chapters that there are between one and the other.
TPN although I have not had the time to read it, but I have heard very good reviews and it is a current jewel of the Jump, so I have been aware before its publication had a great preparation, I think it was 5 years thinking the plot (I'm not sure if this is true) a very serious plot, while on the other side FT had a year's preparation, it started being a very fresh series where his priority was comedy and making bows very short and for me, the best of this series were its beginnings, highlighting Phantom Lord, ToP and Fantasia, but since the 5 day of the magic games had a big drop in quality with a slight rise in Tartaros and peak down with Alvarez, that can not be denied .
My vote is for FT, simply because the other I do not know, but I must say that FT had many problems, but I keep the memory of having enjoyed it a lot.