I’m going to buck the trend here, and say that all the best man/usher gifts I’ve been given have been a bit meh.
I think probably because the couples (at the weddings I’ve ushered/best manned at) have had a to-do list as long as your arm on the lead up to the day, and gifts for the “grooms party” always seem to end up being both a) left until the last minute and then bought with a “that’ll do, another job off the list!” approach, and b) delegated to the groom. (A and B are obviously related).
Fair play to those people above who’ve been given engraved pocket watches, wooden maps and other fab gifts, and I’m certainly grateful for those gifts I’ve received, but the advice I would give is: don’t just get something for the sake of it. If you want to get something nice/with meaning, fill yer boots, but if it’s just because you think you aught to – I would say you’re better off getting them a bottle of what ever they like and a few words of thanks.