I plan to go to UK for an onsite job interview and need an advice about which visa type should I get. "General visitor" and "business visitor" seems like closest matched for me, but descriptions on gov.uk for neither of those does include "job interview" as a reason.
I am a business traveller from Britain, so I have never had to actually apply for a UK Visa, but my experience of similar situations says to me that you shouldn't refer to this as an interview but a 'meeting'. During your visit you won't be being paid in the UK so you aren't a threat. Normally I arrive in a country as a 'general visitor' because I am just 'meeting' not 'working'.
You should also carry a printed version of the invitation to interview, contact details of the person you are visiting, exact details of where you are staying and preferably some means of showing that you aren't going to stay beyond. Part of proof is either showing that you have commitments back home (e.g. already have a job, property lease or mortgage) and that you have enough money to survive on (have a recent bank statement showing you have money). Also make sure you have your return tickets and arrangements clear so they know you plan to return.