Someone will hopefully correct me if I'm wrong, but Im pretty sure reimbursement is the way to go.
When you deduct expenses on your taxes, the value of the deduction is used to reduce your taxable income, not to directly reduce your taxes. Basically, if you have $1000 worth of deductions and currently are taxed on $50k of income, you would instead be taxed on $49k of income. Since that has you at the 25% tax bracket, you effectively save $250 on your taxes compared to not having the deduction. You spent $1000 on work stuff, and saved $250 on taxes, netting you -$750. If you're reimbursed from work they pay you the $1000 and you end up with $0. Since $0 is more than -$750, go with the reimbursement.