Hey JT,
I can't really recommend any of these, but it depends on what you want it for.
If you want to use if for practicing forms, any of them will probably work. Both for Tai Chi, as well as external forms.
But understand that none of these are real weapons. Some of them actually have a guard and pommel made out of wood, with a thin sheet of brass over the top to make it look like metal. There is no weight to balance the blade, and no real strength. It's a stage prop that will probably work for forms, but just understand that. It's not real.
Most of these have very light blades. This is due to the Modern Wushu phenomenon, where people need to be lightning-fast for performance and competition sake. I personally hate these things. They are made of some superlight metal, and again, are just stage props. Really, they are toys and I often wonder why adults want to play with toy swords. I quit doing that when I was about 12.
I personally like to use a real weapon. It needs to be a real blade, made of good quality steel, and beefy enough to actually be useable.
The hilt needs to have a solid guard and pommel, both for strength and to balance the blade. In the Chinese Martial Arts world here in the US, it's hard to find this kind of thing. That's why I've been building my own.
I get blades made by Angus Trim. He makes Western European style swords and I rebuild the hilt to be more appropriate for Chinese martial arts. Angus uses 5160 spring steel, the same stuff used to make leaf springs for trucks. It's a good, tough, durable steel that can take some punishment and hold an edge.
His stuff isn't cheap, costing up to several hundred dollars depending on the model. And again, it's a European hilt which doesn't work so well for Chinese martial arts. I've tried, and a cross guard just kind of gets in the way.
If you want, i'd be happy to discuss the possibility of making something for you, but it's a project that will take a bit of time. Go into the User Galleries, I think on Page 2 I have a gallery with pictures of some of my work. It won't be cheap, but it will be a real weapon that you could actually walk onto a battlefield with, and it will be about 10,000% better than any of these in the link you posted. But if all you want is something inexpensive to practice forms with, any of those will do. Just understand that they are not real weapons.
I can give you links to look at Angus Trim's work, but I'll have to do that this evening as I don't have them on my computer here at work. But if you do a google search for angus trim swords, you will probably find him.
