Suggestions for ornamental trees

[TaylorNotSoSwift]

Looking for suggestions for ornamental trees to go in a line in front of a fence. The ground is quite wet so the idea would be that they could help with that.
The areas is about 50ft long so looking for something that is hardy for a cold wet UK climate but will also add interest.
I have Crab Apples on the other side which are nice but I fancied something different -perhaps Salix Flamingo but open to ideas!

I see you've already got crab apples - that would have been my first suggestion. I have heavy clay soil in my garden that is often waterlogged for part of the year, which is the death of many of my plants! However, my Malus Rudolph has thrived.

You might find this from the RHS useful: https://www.rhs.org.uk/plants/for-places/wet-soils. It includes a list of trees that suit wet soil. For example, Magnolia, Amerlanchier, Prunus. If you've got the space, a Liquidambar could be wonderful.