Well i would recommend tubes for sure for several different reasons. One of the features of a good tube amp is that it responds well to how you attack the note, they can be very dynamic and sensitive to the controls and volume of your guitar which is nice.
I´m a firm beliver in plugging straight into the amp without any junk inbetween, cheeky touch reverb is nice and a wah wah for a change of sound every now and then, for i´m a beliver that its all in the hands, although have you heard santana these days since he stopped using the SG he has a horrible tone.
I digress a little so depends what you want though and what your gonna use it for. If your just gonna have a practise amp then obviously spending loads of cash on a expensive one is a bit of an indulgence. If your playing in a band then i would definetly recommend one.
Valve amps basically are the best but usually at a cost.