Family visitor vs general visitor

I have question regarding visitor visa. I would like to invite my brother, his wife and his two school going children for visit visa to UK. I can comfortably fulfill all the requirements of a sponsor. I will be responsible for their accommodation and living expenses here. However, the challenge is that my brother does not have permanent employment. He works on commission basis(mostly in cash) but has no bank statement or tax returns to provide the evidence. On the other hand, his wife is a permanent employee of a large organization and can provide bank statements, salary slip and tax returns etc. They live in our family home owned by my father. The only registered assets on their names are two cars. My brother is also involved in some volunteer work for a NGO. He also takes care of family properties, manage the hospital treatments/visit for my sick mother and my father pays him some cash for errands and household expenses as he is the only brother living with parent under join family system .
I am confused if I should ask them to apply for family visit where my brother will be principal applicant or as general visitor where his wife can be principal applicant due to strong credential....or does it matter? Will his wife's strong credential cover for my brother’s weak employment/bank status?

A family visit can only apply to the family members of a settled resident, but you have made no mention of your immigration status.

Sorry- forgot to mention that I am a british citizen,married with kids, have a house via mortgage, good income/savings i.e. fulfill all the requirements of a sponsor

Well - in which case it's a family visitor visa.

Each applicant is treated individually. See a previous thread on here when a mother/father were approved, but the applicant's sister was denied.

So your brother needs to present as strong case as possible for his ties to his home country. Show everything he does/has and how settled the kids are at school etc.

Thanks for your prompt replies.

some applicants go the extra mile to show genuineness of their documents, but fall short in showing genuineness of intent. this is one major reason for visa refusal. each applicant needs to demonstrate their ties to back home, and there is no hard and fast rule for achieving this. you as the sponsor will have, in my experience, very little influence via your documents etc.