Neither MA or NJ taxes non-resident remote workers. (The MA Covid exception expired September 13, 2021.) So from a state income tax perspective, it doesn't matter which state you pick.
As long as you never actually (physically) work within those states, your income is taxable only by your home state of Wisconsin.
If your work is going to be done 100% remotely from WI, be sure your employer withholds WI income tax from your pay. Otherwise you'll have to make quarterly estimated tax payments to WI.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
