Have a look at this site :-
https://www.coinwarz.com/cryptocurrency
You can input your hash rates, power usage and costs and calculate what is the most profitable coin to mine at any particular time.
With regard to mining contracts, when I researched them I thought there were a lot of companies who were a bit dodgy either from a scam perspective or from a profitability angle. The key is in the terms of the contract (like anything)
I chose Genesis because I compared a few and they seemed to be competitive on price and professional in approach. They are based in Iceland which I think is ideal. Low local power cost and low ambient temperatures in a first world country, they tick a few boxes for a good business model for me.
Choosing the right coin is trickier. You want one with good fundamentals and prospects over the course of the contract life. Coin price increases help, but does lead to increased mining difficulty and a smaller piece of the pie. Expect yield to drop over the course of the contract due to Moore's Law (new tech improves competitor hash rates) :-
http://www.investopedia.com/terms/m/mooreslaw.asp
I chose DASH and am very happy with my choice so far, but most of the good coins choices are sold out at Genesis right now. I might have a look at Monero though. If I was forced to take a new contract today I'd probably choose Monero. Genesis is offering a 2 year contract that looks like it might ROI in 11 months or so.
If you (or anyone else) decides to sign up with Genesis, please use my affiliate code 65bWBK
It's a modest bonus, but better than nothing.