The more being tried the better.
The Oxford/AstraZeneca one has come in for some criticism as it's estimated to be only partly effective. At least some if not all of the monkeys it was tested on did come down with Covid when exposed to the virus, (although none of them developed pneumonia), and they were euthanased after something like 13 days, so nobody knows what the longer-term impact would be. Maybe these individual animals just wouldn't have developed pneumonia anyway, as not every human with Coivd does, and the vaccine may not have made a difference. Or maybe the onset was delayed. It looks like it was also tested on a very small number of animals before it was moved to the next phase. Another criticism I read suggested that although it may help protect the lower respiratory system against the virus, it might not protect against those cases where the the virus causes brain damage.
The initial animal testing of the Sinovac one being developed in China also had its flaws, apparently - to do with quantity of virus the test animals were exposed to, and exactly where they received the innoculuation and the infection. (The test animals in both trials were getting something a lot more invasive than than shots in the arm).
Edit: just read an article on Imperial College London's website, and this is a completely different type of vaccine to the Oxford and Sinovac ones, an RNA vaccine. There haven't previously been any RNA vaccines licensed for use on humans, although several are under development for Coronavirus, including I believe the leading US vaccine under trial.