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.
i would said yes and agree with you to trading btc/altcoin because the chance for us to make profit is huge and we can buy altcoin with cheap price and sell it when the price is increase. but for limit budget, i would not suggest to trading btc/fiat because you can not get profit as much as if you have big budget so you should stay with trading btc/altcoin.
btc/alt trade would really give you decent profits if you spot a good altcoin but if you choose the wrong one then you would surely lost your money you invest on that particular coin. Btc/Fiat would still do but it would really need huge amounts of bitcoin or fiat to feel the profits on each trade. Thats the hardest part of trading on which you predict the price.