I'm considering buying the big gem pack for 123$ (although the USD/EUR exchange is **** at the moment). My question is - did you guys spend a bit on every/most needed expansion, or did you go for the M19 deal to get 2x Nexus of Fate?

Draft it all!!!

I put up about $30 towards m19 and everything else on draft.

Is it, because Draft is so much fun or is the return of investment better?

To me, both: I enjoy drafting because it's all of Magic in a compact way: Choosing cards, building a deck and then pilot it. That's the only Magic I played in the real world (nothing official, just with a few friends and less than 10 times )

About RoI, there is no single, correct answer for people value costs (gold and time) and rewards differently.

I can provide a breakdown and you make your own decision:

The baseline is a directly purchased pack for 1.000 gold and 0 time, which gets you:
1 Rares of your preferred set
2 Uncommons of your preferred set
5 Commons of your preferred set

All of those can be wildcards and you progress your wildcard wheels by 1.

A draft costs 5k gold, so let's just multiply the above:

5 packs:
5 Rare of your preferred set
10 Uncommons of your preferred set
25 Commons of your preferred set

All of those can be wildcards and you progress your wildcard wheels by 5.

Now let's look at a draft for someone who doesn't want to play it. You'd just pick all the Rares and resign. For 5k gold and about 5 minutes you get:
4+ Rares of the current draft set (3x guaranteed first picks, 1 from the reward booster and several more may wheel to you from the AI drafters)
2++ Uncommons (probably much more than 2, but techically you could get all Rares wheeled and then there might be no Uncommons left to choose)
(53 - amount of higher cards) as Commons (I think the draft has 15 card boosters, so you draft 45 cards + 8 from the reward booster; subtract 3 if it's 14 card booster draft)
50 Gems (750 is a new draft, so it's ~ 333 gold back)

So you certainly get more cards overall for the ressources spent, you have a good chance to get more Rares, too. What's lacking are wildcards and the freedom of choice regarding the set. Afaik an opened draft booster does not progress the wildcard wheels.

Lastly, if you like to draft and draft to win, you spend quite some time, might get fewer Rares/Uncommons. But if you win enough, you can go infinite so you technically remove the gold cost and only convert time into all of those cards listed above.

I confess I bought the welcome bundle out of frustration of running out of drafts some time in July so I am no longer 100% F2P, though I have only used the gems to keep drafting and sometimes go into QC for cheap when I have a green quest.

Conspiracy: Since I got the gems I got more wins and actually went up to limited gold rank and constantly get up to at least 6 if not 7 wins a draft.

Quit bragging. I've opened some doodoo packs recently.

The only money I spent on this game was the welcome bundle, because a wipe is forthcoming and buying specific cards is pointless right now.