If you are a purist and are willing to lug around the individual stomp boxes, I can't argue about the flexibility (and perhaps even the best tone). However, for simplicity I have elected for a multi-processor. I just know I would never bother to set up all the individual boxes I would want. So, I started with a Zoom 506II (not a good choice) and tried a friend's BP200. I was briefly tempted by the Zoom Bfx 708II, but fell in love with the Boss ME-50b. I've had it for about 1 year and would buy it again. Not perfect, but very usable. I like the fact that it is set up like stomp boxes, so very intuitive to use manually. You can also create patches if you prefer. No drum machine (kick drum only, like metronome) and no smart card for recording long loops, but very solid and usable features. Decent compressor/limiter, good eq, noise gate, all metal construction(unlike Zoom), decent tuner and always works.
I'm convinced there is no single perfect answer that fits all people. Another bass player at our church loves his BP200. Try em out at a store before buying.