What top to wear with these trousers and boots?

It depends on your build really, because one style shirt might suit one person but may be unflattering on another. But I'd put the trousers and boots with a fred perry, lyle and scott or ben sherman style polo shirt, I know these brands are fairly expensive so that's why I said 'style'. However don't go for an average polo shirt as it won't complete the look like the others would. Or if your not comfortable with that style shirt then just go for a plain mens v-neck, depending on your skin tone- any colour. But I'd go for a dark grey or jet black. Hope this helps!x