I’ve never seen the point of the Sparks card. I used to have one but the offers were never of any interest to me. Ditto the John Lewis. The Boots card, OTOH - the points really add up, especially if you get extra for being a wrinkly - and the Nectar…
We did once take a M&S credit card, I think, but only because dh was spending a substantial amount on clothing, and they were offering 10% off if we did so. Dh was honest enough to tell the salesperson that he’d only cut it up straightaway - she said it wouldn’t matter! Presumably they got points or something, for getting people to sign up.