Which Style bases to order- straight, rounded, or both?

[volcanohead]

I am planning on playing mostly solitare games, as well as casual games with friends who don't yet own teams; I will be lending my bases to them for games and would like the teams to be even. I have heard good things about the Proline strong bases, and will order some of those. However, I need to decide on the type of front for the bases. Should I go with all straight front bases, all rounded bases, or 12 straight and 12 rounded bases? I just would like to know what would provide the best gameplay with two eleven man teams (no specific offensive/defensive players). Thank you much!!!