It's cheaper per month if you buy a subscription for multiple months... 3, 6 or 12 months.
I wouldn't say any subscription is the worst though, it all depends on how much you want to spend up front and what you want from your subscription. Some folks will want to buy only one month to unlock the gold cap for 30 days while others buy one of the other packages for various reasons. All of the packages offer the same perks and benefits. I am currently on the 3 month plan myself.