For the most versatile( i.e.,room for a passenger, EASY to mount and dismount from), moderately-priced, everyday/training cart, I too would recommend Frontier--I believe it to be the 'industry standard' for its type.
Be very cautious about 'knockoffs' or 'off brands' that "look like" Frontiers, off ebay or anywhere else. I have seen SEVERAL that, though they 'appeared' much the same, were in fact very heavy, or improperly built/not properly balanced, or had other problems--and if your horse is uncomfortable in it, you WILL have problems.
Hyperbikes ARE light, and stable (they have a wide wheel base, and sit you right up 'next to' the horse)-but have no basket-your feet either have to dangle, or be up in the stirrups. They are in essence, a sulky-and of course, there is no room for any passenger.(Question for those who have them...do they have a singletree?)
What you get should depend on YOUR specific needs and wants...I would recommend buying quality, though-no matter what you choose.
Margo