Forget Travellers cheques. My Visa card worked for awhile on my first trip. I informed Visa that I was travelling, but they flagged my card and cut me off. I had to phone and clear it up. The second trip I forgot to inform Visa, my card quit working and I had a hell of a time trying to get through, turned out my card hiccuped or something, it wasn't flagged and it later worked. My debit card didn't work the few times I tried it, so I just used Visa. I also got a spare Visa card just in case mine was lost or stolen. I don't know how long you would have to wait for a replacement, that would leave you cashless if that happened for days.

a lot of the smaller cities don't accept visa, only union pay. best to pay with cash

Foreign credit cards, no matter which, are not widely accepted in China.  You use them to buy an airplane ticket at airport (not at a travel agency), to pay for hotel bills in major hotels,  and at some restaurants if connected to the hotel you are staying.  Oh, and to sometimes withdraw cash from local ATM's.  Other than that, no one else will accept them.  According to some friends, sometimes merchants have to wait almost 6 months to receive the money for whatever you charged, and thus not accepted.

Travelers checks ere accepted at banks who may exchange them. But they are difficult to exchange, even if you present your passport to identify yourself, and do the second signature in their presence, if it is not a mirror image, it will not be accepted. And who signs exactly the same all the time?
Cash now. That has worked for me. Best bet is to bring large denomination bills (like $ 100), in new and uncirculated condition, no pencil, pen or rubber stamp marks on them (if one has it, it will be said is a counterfeit bill). Of course, use a belly money belt, and be aware of pickpockets. Do not flash wads of bills around, and keep between 200 and 300 yuan in your pockets, and the rest inside money belt. If need money from money belt, go to WC and draw money out there.

My bank recommends to cancel the international credit cards after they've been used in China, due to risk of fraud. Someone wrote on this site that the bank needed to be notified in advance for the card to work in China. 

As I live in China, I have a local card for everyday usage. I sometimes use my international credit cards, but only at places like airports and hotels. Would never hand it to a waitress in a restaurant. 

The best way is cash...Gee Ted I don't know why you needed to ask this question under an anonymous user it's not like we don't know you are from Canada a don't you know?? You can use it at the atm to take out cash yes Ted. 

My friend is Canadian and he has had no issue with using a card here. Like others have said, cash is better but if you need to use the plastic then go to an ATM, China Merchants Bank seems to be the best at accepting overseas cards but any with the VISA logo should be ok.

That said, it does depend on where you travel in China, for example my wifes hometown is a 4th tier city and the banks there are limited to a few Bank of China and the rest are mostly local banks.

Rule 1: Get Cash!