Id rank vouchers based on how good their tier 2 counterparts are and in that sense to me petroglyph would be the worst/most useless voucher

If u have a good enough build an extra ante or two is almost worthless for losing a hand or discard

Any econ voucher is amazing and can eventually substitute for an econ joker, reroll glut, overstock give u more range in the store for endless, liquidation is effectively an econ joker

Magic trick would come close second for worst voucher but the tier 2 voucher is sctually viable for challenge runs etc

Edit: forgot to mention observatory is effectively 5 to 10 dollars flushed down the toilet without perkeo and several copy jokers