^ horde ideas are markedly better than Aztec also, with 20% manpower recovery and -25% core cost to go with 20% cavalry combat ability/leader shock.
The problem with Aztec's ideas are scale + scope. They don't have very strong individual bonuses, and they don't have focused bonuses. This makes their idea set somewhat mediocre in 1.8, but not terrible.
Nepal's ideas are not better unless they get de-nerfed. Nepal got nerfed into a pathetic shell of its former self w/o basis.
Also, if you just go by "strong individual bonuses within its focus premise", then go ahead and add nations like Austria, The Knights, Papal State, NED, Denmark, Mamluks, Ming, Hungary, Burgundy (they should have been on your list too), Songhai, Venice, Genoa, The Hansa, Scotland, Italy, and divine ideas to the list.
On a scale/scope setup, the Aztec ideas here are mediocre. Then again, should the Aztec actually have better-than-mediocre ideas? They were not as impressive as the Inca.