I like a rather snug fit for summer use. I hate it when my feel flop around in my shoes, losing power. I like the sensation of being directly connected to the pedals. Very stiff soles. SPD pedals. MTB shoe. Very important that the shoe hold your heel tightly and comfortably. I use shorter shoes than my street shoes. Pedaling doesn't push my toes forward like walking does. Sidi Dominator is a good standard. Shimano can be good - they use a slightly different last. I had some cheapie Specialized shoes that lasted a long time and were OK. Winter socks may be quite a bit thicker and need a larger shoe - but most can be snugged down for summer. So try the shoe with your own socks.