Guitar amplifiers come in so many forms, shaped as well as power. You can choose a guitar amplifier to give you 1-5 watts right up to 100 watt heads. There are also combos which have the amplifier and the cabinet all included in one convenient package. 
The normally larger and more expensive guitar amplifiers with valve’s bring a warmth to the sound that a solid state amp often lacks. The amps you buy as a head which is the amplifier section and generally tonal controls and more effects are heavy to carry around which you should consider. It is likely your going to be taking the amp with you to friends homes and maybe touring with your band so it has to be practical.  

If your looking for a selection of guitar amplifiers that are fully featured, then these are also quite affordable today. The latest option that you may scoff at is the small personal amps. I have the Vox Classic Rock personal amplifier that just plufs into the guitar socket, powered by batteries you plug in your headphones and play. It is really an amazing choice with delay, reverb as well as clean plus chorus. It offers three choices of overdrive plus an extra input to plug in your phone and play backing tracks to solo over. Really enjoyable way to pass the time and practice.