You need 100 of each jewel to make a celestial, and two celestails to make an arcane (along with some runics). Therefore it would be one half arcane per week per gem bounty (100 jewels per day x6), and one arcane per week per Daily Deal (200 jewels per day x6). Drop rates of arcanes from VIP chests are about 40% for a double arcane. You’ll get far more arcanes from the VIP chests, of course, shotgunned across all types. Again, long term, you are far better off just being patient and getting them in Glory Packs than either of these acquisition methods, followed by explore.
So:
Monday-Saturday daily pack for 150 gems gets you 11 arcanes (your choice) over 11 weeks, while 200+ VIP keys gets you 170+ arcanes (spread across all types, avg about 8 of each type, but more likely clustered with some high and low gains)
Monday-Saturday Gem Bounty gets you 14 arcanes over 28 weeks (again, your choice), while a comperable expendature on VIP keys will get you about 140 arcanes (spread across all types, avg about 6 or 7 of each but more likely clustered with some high and low gains)
Short term, it takes so long to get a usable amount of arcanes that it isn’t worth it. Long term, you get an overwhelming number more arcanes from VIP chests, enough that you’ll incidentally get at least a few of the “ones you want”.
As a player in a position that does not need arcanes and missing three mythics, as I said, buying the daily or gem bounty packs outside does not make sense for me - long term or short term. For others that are missing a mythic that could be a game changer for them, it could make sense, short term. Short term, they could be after a specific one and not care about any others including new ones. Long term, if they don’t care about collecting at all, then the choice of two good mythics is obviously better for you than getting even 4 random, or even 4 new ones if they don’t appeal to you. But that is the choice.
Also note that the numbers shift a bit if you don’t have VIP access. The packs look a lot more favorable when you don’t have to give up half your mythics long term in order to indulge in getting a choice of one you missed. If you don’t have VIP access, it is far more close to a choice between “random with fodder” or “guaranteed without fodder”.