SHA-256 is used to mine Bitcoins (BTC). This means, that the only factor which influences the income is the mining difficulty. You can see the difficulty growth chart here - link.
Scrypt is used to mine Litecoins (LTC). This means, that there are 2 factors which influence the income:
Scrypt payouts are converted from LTC to BTC and then added to user's balance.
SHA-256 and Scrypt contracts are also subject to daily maintenance+electricity fees (MEF) which are deducted from each payout. Currently the MEF is 0.0035 USD per 10 GH/s of SHA-256 and 0.01 USD per 1 MH/s of Scrypt.
Once the MEF is deducted from a payout, the remaining amount is considered your profit.
*BTC/USD exchange value also influences the MEF (chart - link).
ETHASH is used to mine Ethereum. As the payouts are provided in ETH, the only factor of influence is the difficulty of mining (chart - link).
X11 is used for mining DASH. The main factor influencing the income is the mining difficulty (chart - link).
ETHASH and X11 contracts are not subject to any additional fees.