The aircraft you use doesn't have to be the fastest aircraft out there. And don't just go for the cheapest aircraft either. Your paying for a licence with which you are going to trust your own and passengers lives. As well as your career.
There is no immediate advantage in doing the rating in a baron or 310 just to get time in those types. Your first job will be in a C200 series or an airvan most likely. Any advantage will be 2 maybe 3 years down the track when you move into twins, and most companies will provide you with an endorsement anyway.
If you can afford it though, and really want to do it in a baron then I personally don't think you can go past JAS at port macquarie in NSW. There are a couple of other schools that do them in barons or 310s and reading through other threads on here will help you locate those companies with good reps in the industry.