I’ve watched all the DC live action movies, even Steel and Jonah Hex, but have only watched a couple of the DC animated movies. So far I’ve seen ‘Gotham by Gaslight’ and ‘Justice League Dark’.
I’d like to watch more and am wondering if there’s a preferred order?
The answer lies here:
Certainly watching them by release date will cover most. But, canonically New Frontier should be watched first. And in theory JL:War is the first of the modern JL films canonically. As it is the formation of the JL, even though some JL movies may have proceeded it.
Okay, if we’re talking about films set before The Flashpoint Paradox (besides adaptations of stories set in their own universe, such as New Frontier and The Dark Knight Returns), the order would look something like this:
For the non-DCAMU movies just watch them in the order available to you. I found several at my library.
this was for everything leading up to Apokolips war
I think from a canonical time standpoint this is probably the most accurate.
Is that a word?
Yes. It was originally a religious term, but it has been adopted by fandom.
the more you know
The canon is the collection of works that make up the “holy scriptures,” or, in this case, the official DC timeline. Anything that falls outside of the canon is apocryphal (of questionable authority, but still of value) at best and heretical at worst. 
Ohhhh like the Starwars Holiday special being Canon but not the last 3 films. Gotcha. Lol
I know Canon from the Camera brand.
Now see, that name comes from Buddhist tradition. It just happens to resemble the Latin word.
Feel free to let your mind be blown again.
I think it can only explode once… I shall let my left arm explode in it’s place! 
I’ll give you the films that stuck with me because they were just epic films. Btw, This list is in no particular order.
I now I’m missing a few and I haven’t seen justice league dark apocalypse war, the second animated Wonder Woman film, and Justice League vs. the Fatal Five.
I reccomend Justice League vs Fatal Five
I’m very confused, is it essential to watch these movies before Apokolips War or not, because I’m very eager to watch this movie and want to very badly.
IMO, I think watching the first JLD movie and either or both of the Suicide Squad movies would be helpful for a bit of context, but frankly it stands on its own as it’s own movie, and can be watched without any prior films being required.
If you want a view into Darkseid, watch Superman/Batman: Apokolips.
If you want to enjoy Apokolips War then this is the list and the order of movies to watch
It sets it up and gives Character Backgrounds