If nowadays one wants simulated original sounds I guess the Kemper profiling amp might be the most advanced solution, but buyers let's still wait a little until the used ones get cheaper.
If you want your individual signature sounds then I think a bunch of several pedals would be better than a single multieffect. By the way you'll achieve the most individual sounds by using several amplifiers parallel, because you'll be able to exploit their different behaviors at different pitches, what some say could make even each pitch individual by sound. Maybe the legendary Santana sound has something to do with this.
Now usability is another thing. Always think of all three stituations: being at home, being in the practice garage or in the studio or being on stage. With lots of pedals in front of you the benefit is that you can somehow connect to them physically and you actually see the effect chain. The disadvantages may be sound loss and technical issues of which there are a lot. (In my pedal days I used to try to limit the sound loss by using active effect-chain-loop-switchers ) Next is the amount of hazzle to handle with, e.g. buying and changing batteries vs. managing a power supply system and not to forget the setting it all up.
Let's get philosophical for a second. Imagine two player personalities which I believe both lie within each of us, and who both want to set creativity free. The first one doesn't want to think of tech stuff and sound an be free to play the music and react to the other musicians. She wants her sound to be already done just manage the interaction of the vibrations. The other one hers some fancy new sound coming out of the instrument and gets inspired by this to play things he has never even thought of before. The second one would be more happy with lots of boxes and wires. The first one may be a kind of purist who wants his legendary setting, which is some little boxes, or he might be the handy guy who doesn't want to spend time in wiring anything up. Even in the latter case he might have the enlightenment to just use a good amp. Still in none of these cases the multieffect pedal would be best choice. Then please show me that player who actually performs on stage and likes to fiddle with the computer system of the multieffect as well!
Now that I have put forth all these reasons against multieffect pedals I must concede that since I am using one of the newer ones with a tube running in it, I don't think anymore of others, to be honest.