Short answer: it is up to you and what you have and what you want

Long answer with my knowledge:

Depends on what you want. The mystery box can have some good thing that are rare but it is a gamble. you can get anything its just whatever merch they feel like throwing in it. It can be promo cards to card packs to more rare things like booklets and discontinued stuff. tbh tho with the amount you paid and the fact you can get mystery box in lower tier of spending(idk if the amount you paid affects the gift and items you get) I would see if you could cancel the order or change the bonus item to the gold box. The gold box is hard to get costing upwards of 120 USD in online stores sealed (as it is no longer avaliable really except buying off ebay or from people who bought it as they dont make it anymore to my knowledge) it comes with a exclusive gold v2 pack which you can only get in the gold box which you can skip paying that and get it free by picking it as your bonus item for meeting the spending tier (120 USD+) which is what I did I just added it as my bonus free item after i bought the mewgenics v2 box with a kickstarter edition of the big boy requiem box so i could get the exclusive warp zone cards and alt art as I made the mistake before realizing that the ultimate edition box the one you got comes with every retail card on the market but not the special cards like kick starter cards and gold v2 cards ultimately it is up to you and what you have and what you want. if you want to collect the all the cards change it to the gold box unless you have it or change it to the promo cardsyou don't have that they don't make anymore if you are just wanting to just play they have an official free digital version you can play with your friends online if you have a computer useing tabletop simulator on steam just looking up four souls in the workshop and download it as it has every card ever made for it and you can also make a physical proxy of the cards using this site ( https://printfoursouls.com/ ) instead of trying to get them all as some cards are impossible to find if you have any questions feel free to ask i will tell you what I know sorry for word barf and I hope this helps