My opinion and experience says that it is better to trade the btc/altcoin than btc/fiat currency. But as many told here, it is an individual experience. Your trading might be different from others. Then go where it is comfortable to you.
yes i am also agree with you that is really one of the best way of trading, i also do trade in btc/alt, i have invested my bitcoins in some potentially good alt coins. and i am also making a good profit from it.