I've looked at both. I ended up just with the reimbursement last year. Technically, sure, if you do a grocery shop that reimburses $10 and pays $10, you could spend $20 and not have "made" any cash on that shop, but it is extra data entry and tax stuffs. Taxes can be a headache anyway, particularly if you have a second business or a regular position.
Did you deduct your miles, did you deduct your work laptop, did you deduct internet and phone? Were they even deductible? Did you donate anything for your own W2 work, did you measure the house and your home office and get your square footage? Did you take any business meetings and keep receipts to get your $8-$12 write-off for lunch? Did you remember to .. bleh. Medical payments, new house, new car, taxes on property, state laws, receipts for parking, toll tickets and on and on and on.
Basically, keep records. Keep good records and ones that make sense. They should make sense to you, but realistically they ought to be easily explained to another human because if you take an account a mess they can't figure out because you think "it's their job, they should just do it" you'll likely regret it. Not saying you'd think this
Short answer -- it's easier to just accept the reimbursement.