I have Boss ME-50, which is an old model but is absolutely fantastic in terms of the range of features. All of the settings are altered by twisting knobs rather than a computerised menu system, which makes it very user friendly. Here is it:
As you can see, there is a huge range of features on offer. There is a separate pedal for distortion, modulation (phaser, flanger, chorus etc) and delay, as well as a pedal for volume, wah, voicing etc. There is further effects in terms of compression and reverb which can be tweaked by fiddling with the knobs towards the top.
There are only two minor gripes - different settings sound better placed in different possitions. For example, a wah pedal will sound better placed directly between the guitar and the amplifier, whilst a reverb pedal will sound better running through the effects loop of an amplifier. Obviously, here you can have all of one, or all of the other - it's completely unavoidable with multi-effects.
Secondly, the patch system is hindered in it's use since there is a split second delay where all sound cuts when alternating between different patches. This makes it limited in its live use.
Regardless, the ME-50 should be regarded as just being one-two effects at a time, but with almost any effect you can think of. The delay and modulation settings are absolutely immense. Until you have played a Muse riff with an additional note played an octave lower using the harmoniser, you haven't lived! This pedal is probably the best purchase I have made in terms of gear since it completely opens your mind regarding what it is like to play with individual effects.
I paid £250 for this brand new and it was worth every penny. You can get it for a fraction of the price now. I cannot recommend it enough.