That's some collection you got there!
As for which Renault to buy. I suggest test driving them all and pick the one that grabs you.
So Clio MK2, Clio MK3, Clio MK4, Megane MK2, Megane MK3, Megane MK4.
When you make an offer don't say something like "will you take $XXX?". That just makes you sound like a time waster.
Go in with an offer where you say "if you accept my offer of $XXX, I WILL buy the car and I'm happy to put down a deposit". It puts the seller under pressure to make up their mind. Hopefully in your favour.