I'd say my favourite character was Renshaw, which I felt I sadly didn't get to hear enough of. However, my favourite narrator would have to be (after a lot of thought) Reverend Wilson, because (no spoilers, I promise) the way he put things is just fantastic. Not the English he used, just his way of looking at and thinking of things. He has an amazing talent for making something so ordinary out as something extraordinary (you could argue it's a religious thing, but to a point; Wilson is way past that point). For anyone reading this, who hasn't read English Passengers, I'm flattered, but I'd strongly advise you to read it.
Mainly, to summarise, I'd have to say it's a story about a journey, while there is a more exact plot, it's the journey that steals the show, and within the journey, the mixing of characters, that often would usually never mix by both choice and lack of opportunity shines though. I'm a sucker for good solid characters, even more so than for a good solid plot, and this book didn't fail to deliver. I may sing praises, but trust me. Or don't. Either way, read the book.