The best option when selecting your mortgage broker is to work with one advisor who is independent and whole-of-market.
Help2Finance works with whole of market and works only with whole of market brokers and can sourse whole of market for the best deal that works for you
Limited brokers can only offer products they are authorised to sell, which means it is beneficial to work with several professionals and ensure you don't miss out on a deal exclusive to one broker.
However, it's wise to approach this with care.
Although you can gain leverage by negotiating with several lenders, if you use multiple brokers at once, it can mean that you submit too many applications, receive a deluge of correspondence, and end up with credit enquiries that damage your credit score.