Which card should I use, or both, as I am confused by the relative benefits of each and the differences if there are, in fact, any.

I have a MasterCard Presidential Plus and a VISA Mileage Plus Explorer (that I recently picked up just for the bonus miles). I am a Lifetime Gold, usually a Plat and occasionally 1K. I have a lifetime UA Club membership, so my annual fee for the Presidential Plus is reduced accordingly.

My goals are to maintain status at Platinum or above, to accumulate miles so that when traveling abroad I can use miles for BF for my wife and upgrades for myself (I buy my ticket so as to accumulate EQM).

SO, should I use one card or the other, or both?

Thanks for any thoughtful input.