Which one is right for me?
All amps have their own unique sound, but the key thing to remember when choosing an amp is the situation in which you’re using it. If you’re a traveling musician who predominantly plays at rehearsals and small pub gigs, a combo with a 12" speaker will treat you well. If you’re a touring musician who owns a van and plays larger venues, you’ll be able to fit a head and cab option in no problem.
One thing that’s important to remember is that 'the bigger the amp the better the amp' isn’t necessarily correct. Some of the most iconic riffs have been recorded on tiny amplifiers! A lot of people believe that a 20 Watt combo with a 10" speaker wouldn’t be able to hold its own on stages, but if you have your speaker mic’d up by the sound engineer it will be more than powerful enough for any show.
Another thing to remember is headroom. If you’re playing distortion-heavy riffs with effects you’re going to need more headroom for your tone, in that case a 100 Watt amp with a 4x12 cabinet will serve you well. However, if you’re playing jazz and focus mainly on clean tones you may find a slightly pushed small combo will have the sound you’re looking for.