Just my opinion here as well.....
For just a 3 years stay financially speaking, Captain at FlyDubai would be better.
As one said, it will keep you current as left seater for a future airline if you find you don't enjoy Dubai and as I read the website for CA pay, it's about 57,000 dirhams/month (11,150 Euros/month) but you are on your own for housing, transportation and utilities which are all included with EK. However, with the prices of housing in Dubai these days, you can find something nice for not so much.
Again, just looking at it from a financial standpoint for a 3 year stint. If you're hear for the long run, EK would be better.
K