Of the COVID vaccines the Astrazeneca one is worst for side effects because of this blood clot thing.
From what I have read, there is no evidence the other vaccines cause blood clots. Astrazeneca is a traditional adenovirus-based vaccine. The others are mRNA. Only the adenovirus ones cause this problem.
It is ironic because some anti-vaxx people object to the newer mRNA technology, saying it is untested and dangerous. It has now been tested more than any other vaccine in history, with more data than all previous vaccines combined. The data proves it is more safe than the traditional vaccines.