It all depends on what you looking for:

Pros for the Valveking:

1. It's a tube amp.
2. It has a good clean channel and can do Classic Rock and blues well.
3. 50 watts of power.
4. Distorts well at low volumes. (under 5)
5. Clean channel ODs easily. (good for bluesy type stuff)

Cons for the Valveking:

1. Horribly muddy sound.
2. No built in effects.
3. Clean channel ODs easy. (Bad for clean songs)
4. Clean channel doesn't get very loud.
5. Not enough gain for metal.
6. Stock speaker iand tubes aren't very good.
7. Not enough gain for anything over Hard Rock.

Pros for the Valvetronix:

1. Handles all styles well.
2. Built in effects.
3. Clean Channel doesn't OD.
4. Good stock Speaker.
5. No replacing of tubes.

Cons for the Valvetronix:

1. It's not a tube amp.
2. Not as loud as the Valveking.
3. Needs a pedal to do heavy metal. (think Nile, Opeth stuff)
4. Stock speaker isn't that great.
Quote by GiantRaven
I'm sure theres a Nigerian king just waiting for you to reply to his email
They're different amps, one's a hybrid modelling amp, the other's a low/mid end valve amp, try them out, see what you think.
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
the valve king doesn't sound much like a tube amp but its probably better than the vox
Quote by Duff_McGee
Masturbate. A lot. Seriously.

<----This is a man