As my fellow Strat-Talkers made clear, there is no generally accepted answer. I have four amps at home – a 5F1 clone, a brown Deluxe, a black Tremolux and an old dinosaur of a '46 Epiphone. My strats sound wonderful through all of them – different, but wonderful. As to which one to buy. Given the usage you intend to make, I'd go for something 15-22W, grab'n'go. Which flavor – only you can tell. What's your budget, how loud are your coffee/bar gigs, and what music do you play with your strat(s)?