Between the two Eco Lifestyle actually has a lot more gameplay. They both actually compliment one another very well though.
I do enjoy Cottage Living, BUT I only have a handful of sims that fits with aesthetic and all of the pack with living in a world like Henford or just that country lifestyle. Miss more gameplay concerning the residents of the world if you don't live there too. Things that are useful outside that for more traditional means for all household is the Simple Living lot challenge, grocery delivery, and cross stitching. Use the first a lot with a lot of household in adding more depth to cooking and more of a struggle.
The pack offers a lot in terms of chores with farm life and busy work, which I like for my sims day to day lives that have it, but doesn't offer much in terms of activities/hobbies. Offers tough challenges especially if your sim lives off the grid and want to make and grow everything.
Eco Lifestyle added quite a lot. With the better breakdown of bills in the base game update, made things like solar panels and power generators more useful. Can appreciate the variety in power surplus to be generated by more eco means or more industrial ones. I use a generator often for my sims homes. I like the random phone calls and chance opportunities you get on the phone which is a nice throw back to the first sims game and some have a impact on your sim or others or their families. (Example: Sims dad called and mentioned that my sim didn't see him often and should come visit. Have three options told his dad he should come over to see him and he said he would. Few sim minutes later and he showed up~)
I like my sims struggling so them being able to just dumpster dive for things, mooch off others and just do that on the daily without paying or buying anything living that Freegan lifestyle is great. Even with some of a few borked NAPS the ones that work well I use often from power shut off day or water conservation day, sims not using electronics,
Eco is a rather gritty pack with the roaches and flies that come with it and having a lot trait where your trash isn't bottomless and things can get gross real fast or you can just ruin the atmosphere and make a world pretty terrible with smog and the like with sims being sick, coughing and just feeling overall miserable because of the environment.
