what sort of walking do you do?? all season? rocky trails? mountain tracks?
there are so many choices now you’d be best going to a specialist outdoor shop and see what they have. fit is variable between brands so you need to try various ones on.
a couple of givens. Vibram soles are almost de rigeur on good boots and Goretex linings if you’re using them in the wet.
ankle support is a variable depending on what sort of walking you’re doing - the rockier and gnarlier the trails the more you’ll need to go to ankle support but for many walks you can get away without as long as the footwear is good.
brands to look at - Salomon, Meindl, Scarpa, Merrell, Berghaus, Salewa etc. Decathlon and Cotswold Outdoor have their own brands and are good.
I have Meindl’s for the gnarlier stuff; Salomon for everyday