Trading altcoin like ethereum in my opinion more promising in the profit gains. Because, they fluctuate higher than bitcoin. So, we can get more profit with ethereum.
Well I guess for me I'd rather start in ethereum than bitcoin because bitcoin is a lot higher cost to buy than ethereum, hence ethereum also possess a good state of its price in the market. Though bitcoin is considered as the superior one compare to altcoin, I do believe in the potential of ethereum too. But then despite of this I'd still dreaming to have my own bitcoin in my account.