gpt4 isn't the flagship any more. GPT-4 Turbo is advertised as being faster, supporting longer input contexts, having a later cut-off date, and scoring higher in reasoning.
There are some (few) valid reasons to use base gpt4 model, but that doesn't make it the flagship by any means.
There are some (few) valid reasons to use base gpt4 model, but that doesn't make it the flagship by any means.