Cannot be told, I think that trading is good on a low price but right now the bitcoin is very high, with altcoins you can to be honest start already now with some nice investing amount.
As I see it, Bitcoin/Fiat trading is a safer option than Bitcoin/Altcoins trading. But, incredible as it seems, the altcoins are showing a good performance in the market, even with Bitcoin rising in price. I think that as long as you have experience you can make a good profit on the altcoins market, but this is a very unpredictable market.