As you do not appear to have any OneWorld Status you would have no Free Seat Reservations ability until T24 on BA
As you do not appear to use BA and OneWorld on a Regular Basis what use would you make of the Miles if you flew BA
Seems you collect miles with a Number of Star Airlines so that means LX^
If its a NEW LX Seat and you feel that you would be comfortable in it go for LX^
Did you really expect any other response on a Swiss Thread.
Finally remember to pack as many important items as you can in Carry-ons [just in Case your Bags do get delayed]
PS: Why do you feel you need to be a member of 4 different Star Alliance FF Schemes thereby reducing your ability to become Elite on any one of them?