Heloo,I want to buy a small practice amp(10-20W) and I'm chooosing between the Fender Mustang I,the yamaha of 5W(Thrx or something like that) and an acoustic G10.Which one do you think will fit my necessities? (I play from blues to heavy metal)
Do you have a guitar store nearby? My recommendation would be to go there and play these amps and see for yourself which fits your playing style. You can also check out reviews and demos online to get a rough idea how the amp sounds. Of course, each amp sounds totally different when the guitar is in your hands - that's why I don't like to make recommendations.

Good luck!