Mystery Box or Yearbook

It all depends what you want to achieve @MizKProductions.

If you just want loads of duplicate items to boost your %bonus multiplier then the Burns' Mystery boxes are the most cost effective way to get there.

If you already have a decent %bonus and are earning a decent donut income from farming, then you can start hitting the Yearbook to slowly collect all those unique items from past events that you don't have yet.
Some of these will come with additional bonus to increase your total % even more, but the non-premium stuff will still all contribute to your income to allow you to farm more donuts.
I haven't done the maths but I would guess that there's probably at least 500% bonus to be had out of the Yearbook if you don't have any of the items in there already but it'll cost you many thousands of donuts to empty it, whereas you could add 500% to your bonus with Burns' boxes a lot quicker and for a lot less donuts.

Easily the Yearbook, the trick is to keep refreshing the Yearbook lineup until you get at least 4 or 5 items you want out of it.

Not to mention you can actually get characters and buildings from the Yearbook, that help you earn more money or add to your overall %.

If your only goal is to increase your bonus % then the Mystery Box is the cheapest with an average cost of 8 donuts per 1%
The Mystery Box only has about 5 premium items while the Yearbook literly has 100's

"MizKProductions;d-271598" wrote:
Read topic

Which do you think is perfect to get Premium Items easily: The Mystery Box (6 donuts) or the Springfield Year Book (30 Donuts)?

I tried spamming the Mystery Box, and got a few Premium Items, but I keep getting the Onda and those food carts and minnow ponds. Then I learn that, if you buy a 30 Donut Item, you can get it for the same price, in the yearbook.

Which would you prefer?

I use the Mr. Burns Mystery Box. It pays out in specific patterns ( I've found 2), but there is a limitation on that: You have to buy them all on the same device and you can only play one game on the device. It seems there's only 1 pointer to the payout table and if a second (or third, etc) game is played on the device it just keeps paying out the same pattern. And the pattern is specific to the installation, so if you change devices or reinstall you'll break the pattern.
Pattern 1 goes like this:

• KMSO3_VL
  
• K_SO1BV_
  
• KMSO3_VL
  
• K_SO1BV_
  
• KMSO3_VL
  
• KM_O1BV_
  
• KMSO3B_L
  
• KM_O1BV_
  
• KMSO3B_L
  
• KM_O1BVL
  
• _MSO3BV_
  
• KMS_1BVL
  
• _MSO3BV_
  
• KMS_1BVL
  
• _MSO1BV_
  

But more complicated.
Pattern 2 goes like this:

• BOMLBOMLBOMV3SKV3SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOML3OMV3SKV1SK
  
• B1SKBOMLBOMV3OMV3SKV1SK
  
• B1SKBOMLBOMV3OMV3SKV1SK
  
• B1SLBOMLBOMV3OKV3SKV1SK
  
• B1MLBOMLBOMV3SKV3SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOMLBOMV3SKV1SKV1SK
  
• BOMLBOML3OMV3SKV1SK
  

But even MORE complicated.