If I had to rank all the seasons so far for my personal taste, I'd probably go:
Season 4 > Season 5 > Fear the Walking Dead Season 1 > Season 2 > Season 1 > Season 3
But my opinion is hardly an average one, I think Season 3 was the worst for me, the conflict got tiresome and there weren't a lot of breathers from it, Season 1 I honestly think is overrated and re-watching it after finishing Season 5 I think it's rather weak in areas, it is differently toned than the rest of the series so I suspect some may prefer it, but honestly I'm not big on it, Season 2 I felt was an extremely mixed season for me, I thought it had good highs, but had low lows, had two of the most impactful scenes in the series for me, but also moved at a glacial pace sometimes
Season 4 and 5 of the main series I felt had MUCH improved characterization, writing, camerawork, and horror elements than the three seasons before it, and were much better paced. Think they finally figured out how to pace the longer episode spans and get better writers/directors on-board, and I enjoyed Seasons 4 and 5 much more than the first three, personally. Fear the Walking Dead is below S4 and S5 for me, but I liked it better than the initial series. I actually like some of the characters unlike some, and I thought they paced the story well, avoided potential interest pitfalls, and concluded on a high note.
But with Walking Dead, people seem so all over the place with opinions, some think its trash, others hate it because it's popular, others love it, some find it entertaining, and some find it a thing to watch. I sit in the crowd that I like it, don't love it, but I do find it enjoyable and I've found it more enjoyable over time than not.