I've recently bought

Boss TU-2
MXR Phase 90
Boss DD-3
Boss CE-5
Ibanez TubeScreamer TS-9
Jim Dunlop Cry Baby 535Q

but my friend who is getting a Boss GT-8 said I should have got a GT-8 too because they're alot better. I know you can choose from a wide range of effects using the GT-8 but are they better? What can you do on a GT-8 that you can't do with single pedals apart from programme effects and save them with a click of a button. Any one reckon I should have gone for the GT-8?

It is really matter of taste. If you friend says that Gt-8 that's his opinion, but you've already got so many single pedals that I think you should stick to them.
Threads like this pop up all the time. HORSES, FOR COURSES.

Also, you have to look at realistically. Here is some realism before the single-pedal-brigade get here...

Buying individual pedals is extremely expensive. Especially if you want quality. "Yeah man but it's only £60 each time.." - 4 x £60 = £240/$550. They are also massive when in a group of 4 or more. Alot don't have true bypass. Often people won't use half of them. They require loads of leads. Tone can deteriorate as each signal is passed. If one pedal feels like misbehaving (it does happen) it can **** everything up. Not all pedals sound good together.

The list goes on and on. Personally, I think people see these amazing guitarists with huge pedal boards and wish to have a set up like that. What they don't always remember is said artist will have sampled 100s and 100s of pedals (because he or she can) to get THEIR tone. I wouldn't be suprised if they are modded as well (to be true bypass, amongst other things).
Once again, its all a matter of taste. I chose the GT-8 because I don't like messing about with individual pedals, but some find the GT-8 too complex. Try out the GT-8, see if you like the sound and the convenience.

Sounds like you've got a good setup there with the pedals, you may be better off sticking with them.
I agree with everything said but my opinion is also that a GT-8 will never sound as good as a "real" pedal but is way better for using in studio and live if you want simplicity.
Schecter C1 Classic
Fender Vintage -57 Ri Stratocaster
Fender Blues JR w/ 12"Cannabis Rex
Mad Professor Sky Blue OD
Wampler Ego Compressor
TC Electronics Stereo Chorus/Flanger
Even though the GT-8 is probably more convenient, single pedals probably sound better, especially in the case of the wah and the tubescreamer.
Aliadiere - sadly has more syllables than goals this season."
Setanta commentator during Newcastle-Middlesbrough. .