If you'd like some other options, we'd be happy to provide some ideas. It'd be nice to know the state of tune of your bike and the places or terrain you'll be riding and how you like to ride though.
The AMS tires seem to have a bit of a problem with durability, though they aren't bad tires when they hold together. I would choose the cheng shin over them though, as they are a bit sturdier.
As Dog86 stated, haulers are a very good paddle and easily outclasses these two molded paddles but the hauler does cost quite a bit more.
Kings Tire makes a paddle called the "turbo" that I like for a straight bladed molded. They are only available in 20" sizes though and can be hard to find.
Prices on all the tires, molded and not, have gone way up in the last decade. The AMS units are the cheapest ones out there at this time, especially if you order them through RMATV when they are on sale. But I caution you, you will get what you pay for.
It's just my normal response to say Hauler before anyone else Sorry. I have not much time on paddles myself so I'm not much help. I did see alot of people running molded paddles at Bundy Hill here this last weekend and I think it would be fun. Its sand and Pea stone pit so I might try that but would never run my haulers in the pit but the molded tires seem to look a bit tougher.
Well with the little time I have the budget isn't looking great. I would like to go with haulers don't get me wrong. Both sets of tires were on craigslist with douglas rims for $125 and I can't decide on one.