Dont have the articles on hand but here is what I got out of reading a couple that look into this exactly:

The 2 big factors are first your skill at playing limited / your win rate and second, how many rares/ mythics you own in the set.

If you dont own many rares or mythics, but are very good at playing limited, then play limited. The rewards, if you can break even or start going posisitve out value buying packs.

If you suck at limited, and dont have time to get good at it, buy packs. Its hard to get good at so dont beat yourself up if it isnt working for you in the beginning.

Buy packs if you have expendable income, love mtg, and dont have the time available to grind positive runs in limited. Trust me, it IS time consuming. However, once you own the majority of rares in a set id advise you to stop buying packs, as you will eventually get all of them with free packs or daily quest gold.

Hope this helped