The fee-free points for rent were enough to entice me. I was actually surprised by the (possibly defunct?) bonus offer for the first five days and was able to take advantage of it. Signup offers aside, the card subs for Chase Sapphire Preferred pretty readily--the abililty to push 3x dining and 2x travel to AA was pretty compelling for me. No annual fee and a generous boost to total available credit lines don't hurt either.

Also, Bilt>Turkish Smiles & Miles may beat Amex>LifeMiles for UA as well (I haven't compared award availabillity, but TK generally has attractive reward redemptions). I have booked using LifeMiles for last minute on UA, but would generally go for AC or TK transfers based on customer service/fee data points I've seen regarding AV.