As far as clones go, the Batman clones made by B&M are my favorite. 

Schwarzkopf Wildcat.

The three medusa floorless coasters or the Deja vues.  Two b&m coasters on the list so far as cloned coasters.  There is a Asian park that had a raptor clone as well.

Galaxi Coaster!

Backlot Stunt Coaster!! 

Schwarzkopf Doppel Looping

I would go with either the Raptor or Manta clones.

Obviously the Vekoma SLC.  LOL

I'm shocked! No one has mentioned two AMAZING cloned coasters (I can think of numerous more models, hopefully this post can spark these ideas to float out). 

Firstly, Intamin Mega-Lites. These small, yet, intense coasters are notorious among Asian and Northern European enthusiasts. Five currently are operating (In chronological order of opening)... Kawasemi (Tobu Zoo Park), Piraten (Djurs Sommerland), Fly Over Mediterranean (Happy Valley Jinniu), Mega-Lite (Happy Valley Songjiang), and Light Speed (Visionland). I've heard many enthusiasts rave about these airtime machines.  

Secondly, Mack Hyper coasters. Yes, they're is only one clone currently operating (Flash at Lewa Adventure). However, a clone of Flash has been confirmed by Mack and will be coming to Land of Legends Theme Park in Antalya, Turkey. The combination of hangtime in the Zero-G-Roll, the plethora of floater over the airtime hills, the comfy, improved Mack restraints, and the world's tallest vertical loop, make for a great overall experince. 

I'm surprised no one has touched on the Ispee...Oh wait. @Maverick44 or @goettablitz, I'll let you take that one.

I mean if I gotta.......lol

X2 at Magic Mountain

 Have to go to Japan for its clone so it still comes off as pretty unique. Wouldn't mind seeing some new ones with new layouts.