I liked season one better simply because it was much more thrilling, a missing Will who we barely see or hear of, nobody believing Joyce at the start putting you the viewer in a frustrated state since you can tell she isn't lying, and Eleven being under the constant threat of being recaptured. A whole more mystery vibe which was thrilling to say the least.
That being said, season 2 was epic in it's own rights, especially since it brought into play a more frightening antagonist in the mind flayer
she seems genuine. Isnt she the one who once had blossoming career and ruined because she couldnt stop stealing things from department stores even though she was a millionaire and couldve just bought it?