hey great post, I would say that Swimming is the most complete activity but you said It does not build muscles, they are very important in our life time, we need our muscles for everything even for doing things we dont imagine, so the best thing is to do a mixed routine, swimming and other activities.
I love playing football/soccer it generates me lots of adrenaline and excitement, sadly this game has a high risk of injuries and joints impact because its nature as an impact and force sport.
Greetings from Venezuela.
RE: Yoga, Gym, Aerobics, Swimming - What is the best training for you