I get absolutely attached to my starter, and would never, EVER box my starter. Sometimes I leave it in the box because I want to train some specific Pokémon or am breeding Eggs, but it always returns and is the main Pokémon on the default team.
In the old days, my default team was pretty much the starter, the flier, the surfer and the general obstacle remover. Nowadays when you don't need HM users, I found myself getting very attached to my whole team - as in, I haven't raised many other Pokémon yet, haven't rotated much. I should, I like raising different Pokémon and feeling like each one I have is an individual, with memories of fun times had with it.