Benchrest competition what gun to start with

I would suggest you try going to a benchrest match and ask questions. Most shooters there will let you try their guns. Talking with other like minded fellow airgun enthusiasts and shooting many types of airguns is the main reason I participate in the EBR.
There are a lot of very good guns out there and I think they all are capable of winning matches. The only unknown is what feels comfortable for you.
For most people, a top quality airgun cost a lot of money and being able to shoot a variety of guns first hand and asking questions will really narrow down your choices.
Good luck.