It maybe looks like a strange question, because none of these scanners is probably your system of choice for neuroimaging research, but I would appreciate any sharing of experience.
We have a 3T siemens trio scanner used for research either for structural or functional MRI. We have performed many different types of studies including distinct stimulation (visual, auditory, olphatory, etc) and it worked well for all of them.
Thank you! Yes, I would prefer Trio as well :) So far it seems to be the best research scanner. But other Siemens scanners can be used for fMRI as well.