Lawler>Condit>Penn>Rory>GSP>Serra>Hendricks>Hughes
I know Rory didn't win the belt but he's at that level and I want to count him.
Lawler always goes forward and is a vicious striker so it's self-explanatory.
Condit is the same, and a more diverse striker, but he's easier to take down which can lead to boring fights, and he fought very defensively against Diaz.
BJ Penn has mostly exciting fights.
Rory MacDonald has had some great fights, but the jabfests put him behind the top 3.
GSP fought very cautiously in a lot of his fights, leading to many decisions. However, as a striker he's fun to watch, and he's also entertaining to watch just because he's talented.
Matt Serra is this low jus because he doesn't stand out. He's not a wrestler so he doesn't look to win by control, and he had power.
Johny Hendricks' most redeeming quality is his power, but his grinding style puts him low on the list. He looked to win by control at points in all three of his last fights.
Matt Hughes had some great fights, but stylistically he's the most boring. He's a wrestler who didn't have a huge amount of power.
None of these fighters are boring though. They all have something that makes them fun to watch.