Check the "fight of the year" in the past 5-6 years, definitely worth watching. Last one was the Shogun vs. Henderson in 2011, a lot of fans (including myself) regard it as the best fight of all time. You also have to watch the Silva vs. Sonnen I, Frankie Edgar vs. Gray Maynard II and III. Try to download some UFC unleashed episodes, they always show some great fights.
I personally enjoy the middle weightclasses more. From Light heavyweight down to Lightweight. Not really a fan of featherweight, Bantamweight and the new awful, awful flyweight.
Great fighters include BJ Penn (a bit old and past it right now but still active, one of the most entertaining fighters), George St. Pierre (current UFC Walterweight champion, regarded as the No.2 pound for pound after Anderson Silva, a complete fighter has no weaknesses), Junior Dos Santos (Current UFC heavyweight champion, regarded as best boxer in MMA), his nemesis Cain Velasquez and of course Shogun Rua (because Woody

) and Dan Henderson.
As for past fighters, Chuck Liddell, Randy Couture and Matt Hughes were great fighters. Outside the cage, though, the most entertaining fighter of all time is Chael Sonnen
