I've got a PX4 (latest is PX4D for bass/guitar, at £99, or PX5D at ~150, which has some useful improvements like usb recording and external footswitch(es?) - but that's getting a bit ££).
PX4 has aux in, which is handy, but never much liked any of its distortion sounds, so I find it best used clean. But you probably couldn't go far wrong with one of those - the competition's not really got anything better feature-wise
Although the smaller PODs have aux/mp3 in, they *don't* appear to have a metronome, which is a pity.
Vox don't do anything comparable.
That Digitech dosn't look too bad - I guess one thing it lacks is an aux-in, and its bigger brothers don't appear to either.
The Zoom stuff also appears to lack aux-in, but may be ok otherwise. Boss don't seems to do anything with a metronome either (apart from the JS-08 which is pretty damn expensive)
Straying a bit off-topic, but I did a search for similar stuff a while back (already using a Tonelab LE in the covers band I was in), and came across the Digitech GNX4: stereo aux-in (and mic i/p too), onboard multitrack recorder to CF card, plays mp3s off CF, on-board metronome/midi drum machine (and can play midi drum tracks off CF card iirc), plus assorted I/O routing/compensation options with external amps. Also recording to pc via included S/W. Hence it's related website:
guitarworkstation.com - lots of useful stuff on the related forum (there's also another digitech site for it which has patches and user created mp3 samples).
It's a little old and recently discontinued AFAIA - I picked one up new for 199 recently (normally 300+, list was 500 at one point !) - but sadly not being replaced in a similar form.
Unlike the Tonelab which has pretty decent amp sounds out of the box - and easy to dial in new ones - the Digitech's don't really show it off. There's a sound engineer in the US who's generated amp/fx patches for it based on measuring frequency responses of real amps at various settings, they're supposed to be pretty decent (but more ££).
