Nobody replied to this yet, so I will.
I have played only small amounts of both Endless Space and Endless Legends, under 30 hours each. I did not get Endless Space until I got the 50% off coupon from Endless Legend's Founder Pack.
That said, it seems like Endless Legend is a really well done game. Balance issues exist, but they are generally getting stomped out by patches. It feels like the game has massive bonuses for AI, but then so did Endless Space. It has more of a Civ-esque expansion style in having a hex grid map, but each region can only have one city, turning each region into a solar system essentially. Combat is a lot better and more intuitive to use imo, though auto battle still exists if you prefer to focus on other things. I have not yet fought any major wars, though I like the general design and composition of armies. I additionally like how the natives system allows you to fix potential holes in both your military and management areas of your nation. I have read that the end game is lackluster, I very rarely finish games however, so I can't comment on that. Also of note is the extreme amount of variety this game has. No 2 civs play the same, and attempting to play them the same will not work.
I'm not sure it's worth $40, but it certainly is a good game worth getting. I do not regret getting it for $40 myself at least.