My opinion is the complete opposite. I find FT a lot better than RM. I've read FT countless of times, in fact if I would make a statistic of the amount of times I read chapters of a series, without any doubt FT would be number one, even before Naruto or OP. I read RM once, never had the urge to read it again after that, unlike FT where I keep reading chapters over and over again (and some chapters I really read a lot).
Whichever of the two series you prefer, that's a complete subjective opinion, however there are still limits to how much you can blow things out of proportion. Your metaphor is plain BS, you can't even take such a statement seriously as whether you prefer RM or FT, it's a fact that those two are extremely similar to the point I find that Hiro made them a bit too similar. So saying that FT is a picture book from a 5 year old while RM is a prestigious book is a metaphor that belongs in the trash, especially considering that there's one point you can't deny and that's that the artwork of FT is just way better than that of RM (and I'm not talking about the fanservice or anime), which is logical considering FT is younger and his skill improved. The artwork from the first FT chapters resembles the artwork from RM way more than the style in the current chapters. That is unless of course you like that retro-style artwork more.
That you like RM more than FT, that's your opinion, however don't make metaphors that don't make any sense at all and that belong in the trash. It's very hard to take your opinion then seriously.
Personally I find FT better than RM because, outside the better artwork, the end of RM sucked balls. I really really hated how Hiro ended it, he just pulled a Deus Ex Machina. I really hope he doesn't do that with FT. But above all what annoyed me the most in RM was just simply it lacked any kind of basic structure, it was just random and I really had the feeling that Hiro wrote things when he was writing it and as a result it took away the excitement of a lot of things. Especially towards the end he was blowing things up. That's how Hiro writes, FT has that problem too. Both FT and RM really lack 'depth' in their stories, especially compared to OP or Naruto (and this is why Love Cook these days gives those negative comments all the time, IMO unjustified as Hiro has always been like that). But that's also the reason as why FT is so popular, it breaks with 'normal' things. For instance out of the blue a 7-year timeskip where they actually got 'weaker'.
The difference between FT and RM is just that FT has a way more solid basis, namely the structure of that they have a guild where they always go back to, not just as a place, but really a solid structure in the story itself. RM lacked that, especially towards the end it started to get more and more random, like Hiro just made it up when he was writing the next chapter. Whether you like that kind of writing style is something personal, but that doesn't take away that no matter which one you like, both of them are very similar. I prefer FT, you prefer RM, but your metaphor is BS as then, seen the popularity FT has these days, RM should belong in the same list as Naruto and OP. I always have considered that Hiro learned from RM to avoid certain flaws in FT which RM had.