It really depends on your skin tone, but I definitely prefer gold or a leather (brown or white) strap. For me, gold looks best, but if your skin has blue undertones (you look better wearing green, blue, white than wearing red, orange and beige and your veins in your arms are blue), silver will look best.
Silver. Silver, though more commonly found, is actually technically the better metal (over gold). Look it up. The only reason people want gold more, is because it's rarer, meaninng it's more valuable (it's worrth more, if you sell it). But yeah, go with the silver
colorful watch is much more fashionable esp if it's flattering with your outfit and skin tone. I think it depends on your style. What is your style or what kind of watches do you have in mind (so to answer your Q which is cuter, all can be cute)? I like silver more, chic and good for any outfit.