what is the best mulit-effects pedal (with an expression pedal) for around 200$??? i would be using it with an epiphone valve junior half stack. some suggestions i thought were the Digitech RP150/250/350, the Zoom G2.1U and the Line 6 Floor Pod Plus,

Between the Digitech and Line 6. if you go with the digitech stay above the 250 series. But i say go to guitar center and play around with them.
I would probably go for the Rp250 or if you can afford it rp350. Dont get the Zoom, it sucks.

The Line 6 Pod is pretty awesome too if you can afford it.
The Pod is awesome but its best when your running it through an amp with more sound capabilities.

The Rp series is much more flexible and can nail tones easier but for you it is a tough choice.

Overall the POD is the best IMO, not sure if its the best for the Valve Jr.

You're gunna have to decide between a Pod or Rp250/350

But the Zoom is utter crap.
a couple guy's here love the line 6 pedals with the VJ's.
Playing on some new gear....review to follow
No experience with the floor pod plus, but the xt live is great with the Vj.
Dean Icon PZ
Line 6 Variax 700
Dean V-Wing
Dean ML 79 SilverBurst
MXR M 108
H2O Chorus/Echo
Valve Junior (V3 Head/Cab and Combo)
VHT Special 6
Phonic 620 Power Pod PA
Wampler Super Plextortion
Line 6 Pod HD
Line 6.

Tonnes better than digitech and zoom.
Fender American Vintage '62 Jaguar
Fender Crafted in Japan '62 Telecaster
THD Flexi-50 + Vox V112HTV Handwired Cab