Don't ditch your reward visa just yet. If it doesn't have an annual fee keep it around to keep your average account age up. Just switch usage.
Ultimate Rewards (Chase), in general, are valued slightly more than Membership Rewards (Amex) but value is in the eye of the beholder. I like the MR program and the ways I can use it. I keep the two Amex cards as I had the Amex Everyday Card before I went into the charge card venue and keep it as a backup card. I think this year I have put maybe 500$ on it meanwhile putting over 20,000$ on my PRG.
As you generally go with the lowest fare it would seem like a good idea to look into the Alaska Airlines program as they network with many airlines (not United, Jetblue or SW domestically) but would allow you to collect miles on AA, DL, AS and soon VX domestically & many international airlines