Strictly based on location, my choice would be the Renaissance Ginza Tobu. Although I've never stayed there, my impression from the reports of others is that their rooms are probably the smallest of the hotels you mentioned. Nevertheless, IMHO Ginza is a far superior location. Things are more spread out in Shinjuku and it is beastly hot & humid in August. You'll be much more comfortable in Ginza and there is a greater variety of stores closer together. In Ginza, you're also more easily accessible to public transport and to other sites of interest.