I like the lore from Flee Mortals! I like FM! more than the 5e monster manual. But I like A5E best.
FM! is a bit over-engineered. I compared the Ogre from 5e, a5e, and MCDM. A5e is best for me- cool mechanical stuff, but not too heavy.
And their monster entries are the most USEFUL for me when I'm in the middle of running a game- little charts of signs that there are ogres in the area, what ogres might be doing, same loot for encounters, names, etc.
You can use them all ofc- but when on the fly I go to grab a monster, and I look at an ogre for each, I end up using the a5e ones cuz they're the most useful (cooler than 5e) and don't have a ton of mechanical stuff to parse through (FM!).