Which do you want higher: risk or reward?

Two scenarios to consider:
You pay me $1 if I roll a 1-5 with a die. I pay you $3 if I roll a 6.
3:1 odds on something with a 1:5 chance of winning?

You pay me $1 if you roll a 1-4 with a die. I pay you $3 if you roll a 5 or 6.
3:1 odds on something with a 1:2 chance of winning?

Jack' makes a good point. But you have to either convert the pot odds to a percentage, or convert your win percentage to odds. Whatever suits you is fine.