I think you need 6.
1. Arona
2. Wand
3. Wand
4. Wand
5. Chuck
6. Chuck
Yeah he lost two on Wand, but that was the best Wand there was. They are just intense fights. They have everything, bad blood, back and forth, motivation of purely harming your opponent (not winning, just fucking this dude up).
The Chuck fights show him doing exactly what Chuck was stopping and knocking out in the UFC. He outstruck him and outwrestling him. I think he is basically the litmus that shows at that time, PRIDE middleweight was obviously superior to UFC LHW.
Each one of those fights were some of the building blocks of MMA's advancement, and belongs in MMA history.
You can also watch both Rua fights, but they aren't good showings of Quinton. They are worth watching, and should, but I don't think he should've been in the ring for either of those.