I really love Vikings. Unfortunately, I preferred the season 1 and 2, yet I cannot say "no" when new episodes are released although most of my favourite plots and characters are, well, finished
I really like the overall theme of norsemen travelling and kicking ass all around the Europe, I like how he series are being made visually, the climate is really harsh and immersive. Music is also a great thing, especially Wardruna tracks - I do like that band a lot, too.
Haven't really watched Game of Thrones at all, so I cannot really refer or compare the two. I think I wouldn't watch GoT, as I prefer series that are rather short (Band of Brothers) or with not so frequently released seasons (Black Mirror, and as here, Vikings). I just don't have too much time for TV series and here, with Vikings, the seasons come out with long breaks.
I would definetly recommend Vikings!