Which will be more difficult to pass?

We are applying for COS for October and I am wondering which is rejected more, COS or the visa application? Our COS was rejected the first time due to a problem with the employers job post. If it is accepted, are we likely to have the visa accepted, or is the visa just as difficult as the COS? I am American and the job is Ph.D. level, so I don't think that points should be a problem. Thanks,

if your employer had applied the cos properly, following all the easy to follow instructions, the cos would have been issued.
For the visa, it is point based system, if you score points (they are in fact checklist rather than points and are not dependent on qualification or salary or anything else, while applying for visa), you are sure to get a visa. On the other hand, if the instructions are not followed and u miss something (eg, maintaining bank statement of certain amount for 90 days.. your balance drops down by even a £1), you can be sure the visa will be rejected.
The whole process is impartial of nationalities, everyone is treated equally