very long post, beware 
my experience with samplers:
i started with an akai s950 (unexpanded) which i still have and will upgrade with usb drive and led display soon. probably the best one i ever used features wise if you donāt consider the ram limitations and clunkyness of the small old display. great features, multisampling, variable sampling rate!!! this is something i used a lot both to save memory and to process sound. the onboard filter is great as well, plus you get a nice bonus sine generator
the sound of this machine is so cool is almost unbelievable! despite (or thanks to) its 12 bits converters this spits out sounds that are almost solid matter! my drums never sounded so good as on the 950.
then i added an mpc 2000xl , great gear but with its limits re: multisampling and live performing, so i upgraded to an mpc4000. this was a real beauty. glorious machine with tons of modulations, i often used it as a synth multisampling simple waveforms and looping them as oscillators. great i\oās (even mic in with phantom and phono preamp with ground). great visual feedback (piano roll like view of sequences! yesss!). cons: it was huge to bring on stage and prone to some malfunctions, had to repair it thrice. sold it in a bad financial moment, missed it a lot. then years later i bought an mpc500, it was nice but too toyish for my needs, so brought it back to the shop the day after and purchased a mpc1000. upgraded the pads, installed jjos2xl (great alternative firmware) and fell in love. the 1000 is a great little one: i did tons of live sets with the 1000 alone, or with it and a micromodular, or with it and another single multitimbral synth (blofeld, jv1080). jjos adds incredible value especially for performance, new clever ways to change patterns while playing etc⦠then i felt the need for bigger pads and swapped it for a 2500 (with the same jjos). same experience, better user interface, bigger and heavier. then sold it, bought maschine, loved it, then felt the need to get rid of computers for performing and go back to hardware only. tried the octatrack. loved it for its open-ended, experimental nature but had two issues: 1)iām not really a fan of step sequencers (even advanced ones like elektronās) 2)the sound of it is good when you go minimal, but mixing different busy tracks on it? gainstaging nightmare. overall i always found it sounded dull compared to what i used before. swapped it for a er-301\monome grid + ansible combo. dream come true. the er-301 is probably the best instrument i ever used, it sounds so much better than the octa and you can basically program it to do whatever you want with samples, live recording, synthesis, you name it. of course it lacks the sequencer, but you can build them inside it to suit your needs.
then felt the need to something a bit more physical and i was missing the mpc world. bougth an mpc live mk1. now i have the best of both worlds, crazy bizarre totally customizable on the 301 and mpc workflow optimized for the new millenium on the mpc live. the fact that you have so much ram on these newer mpcs means you can get creative throwing in entire songs, and then chopping only the parts you like and building programs out of them. iāve chopped a shitload of my unreleased tracks. you know, often you have tracks with wonderful sounds and phrases but that donāt go anywhere musically, thatās perfect food for a modern sampler! plus the autosampler feature built in means i can conjure up a great patch on the modular, use a midi-cv interface and let the mpc sample it automatically (multisampling) and then play it like a poly synth!!!
the effects and instruments inside were a huge great surprise, they actually sound very good (where classic mpcās effects were basic to say the best). i think there is still a lot of space for improvement (in the mixer section, in the sustain loop department, in the ānext sequenceā performance options etcā¦) but this time akai nailed it, the whole line is a great improvement on a classic machine!
the live and the x have phono preamps built in. i have tape machines, cassettes players and turntable hooked up to my main mixer and a dedicated out to the mpc so iām always ready to sample and chop. samplerās heaven, eventually! <3
(p.s.: some last considerations. the new mpc line feels a bit like working on a computer, or an ipad, with its touchscreen and advanced graphics. this is a pro but it lacks that aura of dedicated, ninja style unit that older mpcās had (if you get what i mean). if i had the cash and space i would pair it with a 1000 with jjos2xl, for sure. they are different and differently inspiring. but: keep in mind both 1000 and 2500 have one big issue: all buttons are prone to die sooner or later, they are badly engineered and very fragile. if you use them a lot and perform a lot youāll need to change them sooner or later. the mpc live rubberized buttons feel eternal in comparison. iāve seen some users on mpc-forums did some mods to the buttons to have them more solid years ago. that was my only complain on the 1000\2500 line.)