I want to know whats the best cab for the peavey 6505+ head, Iv'e heard that a mesa boogie is good , did the peavey 6505 cab is better ?? or a Marshall maybe , randall .. what you think ?? price/quality like between 800$ / 1000$
Mesa 412 is a tried and tested solution.

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Peavey cabs are terrible (well, they have terrible speakers anyway), unless you can score one for like $150 (happens occasionally), then get new speakers. This can end up being more costly in the end, as you most likely won't find a good Peavey cab (6505, JSX) for that cheap, and good speakers are about $60 a piece.

your best bet is a Mesa or Orange cab. They usually go for anywhere between $400-600 used.
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IMO 6505+ Mesa and Orange cabs combinations are really over rated. If you are looking for that classic sound than by all means, go for it. But it's become so overused at this point. I run my 6505 through a Randall XL from back in the day and I have to say it's a very interesting presence heavy sound. If you can pick up a cheap older randall cab, go for it. I have never had an issue with a randall cab (sound wise, or durability.