[Benjamin]

Go.

1). The Mole US
2). The Apprentice UK
2). Big Brother UK
4). Survivor US
5). Big Brother US

[Liam-]

1. Big Brother UK
2. Survivor
3. BBUSA
4. The Amazing Race
5. Shipwrecked

[Samm]

General Big Brother US, UK, CA etc, Charm School, Survivor, The Apprentice, America's Next Top Model

[Benjamin]

Oops, forgot The Apprentice.

[Jack_]

1) Big Brother US
2) Survivor
3) Big Brother Canada
4) Big Brother UK

[reece(:]

BBUK
Survivor
The Apprentice
BBUS/CA
The Amazing Race

[Pete.]

1. BBUSA
2. BBUK
3. Apprentice UK
4. Survivor
5. Charm School

[Bluerang1]

1. BB USA
2. The Amazing Race
3. Survivor
4. Big Brother UK
5. The Apprentice UK

oop

Honorable mention: The Challenge

[Anaesthesia]

BBUS
The Apprentice UK
Come Dine with Me
Hell's Kitchen US
Geordie Shore

[Alf]

I'm a Celebrity Get Me Out Of Here
Big Brother UK
Apprentice UK

I think they're the only ones I watch.

[Shaun]

errrrrrm

1) RuPaul's Drag Race
2) The Apprentice (UK)
3) Big Brother (UK) (inc. Celeb editions, hijack, whatever)
4) Playing it Straight
5) The Mole (US) - didn't see much of it but liked what I saw.

i'd include the bake-off but it's really not that much of a gameshow

[Marc]

Oh my god. Difficult.

Survivor
Mole
The Amazing Race
Big Brother US
The Apprentice

[Cal.]

1. Big Brother (UK)
2. I'm A Celebrity...Get Me Out Of Here!
3. The X-Factor
4. The Voice
5. Dancing on Ice (even though it's ended!)

[armand.kay]

1) survivor
2) big brother can
3) big brother us
4) the mole
5) the amazing race

[DrunkerThanMoses]

Amazing Race
Survivor
Big Brother USA
The Apprentice (UK and US)
Mole USA

[Cal.]

I really liked Shipwrecked as well

[Headie]

1. Big Brother Canada/USA (same format)
2. Big Brother UK
3. Survivor USA/South Africa
4. The Amazing Race
5. America's Next Top Model

Was tempted to rank TAR higher, since it usually works well even without a good cast (thought not always) and when it does have a good cast, it's amazing viewing. Surprised no UK channels have picked it up considering the format is universal.