If nothing else it should be about how much time you and your game group want to spend on a single play.

TI3 takes a long time... 8 hours to 12 hours. (unless you have a super group of players with no AP) Eclipse will take about 5 hours the first time you play as your learning the rules, and under 4 hours once you know them. I can say that I am able to find more people willing to play Eclipse just because of game time needed.

I would recommend Eclipse... unless you have a group of gamers that can/will invest a whole day to play one game.

Well, even here you'll get some other side responses.

I enjoy both games. I find TI3 to be far deeper, richer, and more engaging, but it also comes at a "cost" of much more time commitment. I've talked about TI3 games months later. I haven't played any games of Eclipse that leave an epic "imprint" on me that I talk about even days later, much less months.

Eclipse to me is a very streamlined, simple, and easy-to-use economic/exploration mechanism that can produce some of the coolest "space fights" I've seen. The reason for this is that while everybody has the same three ship types (basically), they can be upgraded in a variety of ways. Due to the availability of different technologies, or the lack of certain ones in some games, because of the random draw.

You can have a game (like our last one) where the player who won never got an upgraded weapon and had to rely on swarms of armored ships with laser precision. The player in second had very powerful ships that were higher risk (needed 6's to hit) but would kill any other ship on the map in one hit; nobody wanted to roll against those odds!

That being said, it misses a lot about what makes an epic game truly "epic" like diplomacy or the galactic council of Twilight Imperium (which was a really cool feature), it doesn't have a "true" tech tree (which I like, but some don't), and it has a defined turn limit and a "count your victory points" win condition (as opposed to achieving pre-defined objectives). All these aspects are fine with me, though.

That "fairness" being said and done, I could not stand TI3 even though I love the idea of it so much, a big epic space opera. Instead it was a lot of worrying about minutiae, should I spend my influence on this or that, how much have I already spent, how many activation tokens do I have, how big is my fleet capacity, and the biggest stick in my craw was the "Puerto Rico Action Selection Mechanic" which I hate." If I want to move, I will move on my turn.

And that's where all that simplicity in Eclipse won me over. I can immediately see the resources I have, how many I will have next turn, I have no size or move limits on my fleet, and I don't really worry about the economic side other than "colonize everything all the time unless you're running out of money" a system I can wrap my brain around (it's a little more complicated, and you can play some games with that side, too)!

but despite those memories the game is simply broken/uninteresting out of the box (including expansions).

Eclipse is definitely more streamlined and more elegant than TI3.

But when talking about replayability, TI3 clearly out weights Eclipse.

More (or less) chrome doesn't make a game more or less replayable. Providing a wide diversity of gamestates does.

Only if those gamestates are significantly different. I haven't played Eclipse quite enough to know if that's the case. But in almost 6 years of playing TI3, I'm not even close to tired of it (whereas with Eclipse, I still like it, but it's not my go-to game like it was the first couple weeks).

If your TI3 play numbers are correct (they may not be) you've played 18 games of TI3 in 6 years.