Due to him being nothing but a cameo appearance in S3, I've not included that in the poll

In season 2, he lied a lot and tried to cover up his work, which made sense but was also kind of unappealing. Season 4 he was really nice to Eleven and helped her get her powers back, so I prefer him then

I have to go with season 4

He was a lot more smart in Season 4, and was also a lot more interesting.