I don't have a copy of FantasyCraft, but I have seen bits of it and heard other things, which makes me think that for what it does, it does well.
But I have 13th Age and prefer it. I pre-ordered it shortly after it became available, due to what I saw people doing with it and what I saw people saying about it. It is good for me because it fits between the narrative-y type stuff that not everyone likes and the stuff that people like with d20 because it's familiar ground they can trail their own footsteps over.
It's also a lot lighter than FantasyCraft. I don't really want to play anything that heavy, much less run it, unless I really have to in order to play something. I'm playing and sometimes running in a system right now that is crunchier than I prefer, and I'm not enjoying that aspect of things as much.
There are some parts of FantasyCraft I really like. The way the feat chains were done made them clear, powerful, and fun all at the same time, and the racial feats are genius. There's a lot of good stuff there, and I'd say it's my favorite system for "Rule System as Laws of Physics" type play.
But, 13th Age is ideally suited for high fantasy. It seems to have imported the feat chains from FantasyCraft, and attached them to the various class abilities as well. The escalation die is great, and the monsters are great (that was the biggest issue I've found with FantasyCraft). I'd happily play FantasyCraft, I'm already planning my 13th Age game.
If I had been exposed to Fantasycraft when I first got into RPG's I likely would have loved it as I'm intrinsically drawn to huge amounts of crunch. However, in the few short years that I've been gaming my tastes have already evolved significantly. I still want lots of character options, but I now want a much more streamlined game. 13th Age fits the bill perfectly and seems to be a game designed specifically for me. It's crunchy where I want it to be while hand-wavey in the areas I don't care about details. It also brings in cool mechanics that I think dramatically improve play without adding complexity, the Icon relationship system in particular is fantastic.
The lower level of crunch has another big advantage beyond simple personal preferences: it's a lot easier to get people to play. 13th Age is extremely newbie friendly so I felt very comfortable introducing it to my brother-in-law and his two teen sons even though they had never played an RPG before and essentially didn't even know roleplaying existed. I would not have tried introducing Fantasycraft to them because it is just so much more mechanically complex (the 12 year old would have been especially overwhelmed). I also feel it is easier to sell my friends who are veteran D&D players on 13th Age than Fantasycraft because of the lower barrier-to-entry. I'm sure they could learn FC, but I doubt all of them want to spend the time to do so.
Whilst it is crunchy, it is crunchy in a good way...for the most part. For example, whilst you have complete control and freedom to create pretty much any monster/creature you want, the prep time is painful and a chore
13th Age, nothing much wrong with it apart from the odd thing where characters from certain classes (example; Thief) have to remove a feat/power they've been using in order to choose something else at that particular level. I've heard the reasons given why this is ok, but I don't buy it. You suddenly stop being able to use Feat 'X' but you can now do something different (and that different is not even an upgrade on Feat 'X' either)
I like 13th Age. It's foundation seems to be a lot simpler and more versatile at the same time - mostly because it's lighter. If I go for a game with narrative physics so to speak, 13th Age all the way. If I went for a rules-as-physics as a game, I'd rather take 13th Age as a foundation and graft new stuff from FantasyCraft onto 13th Age than the other way round.