If you have to pick, Kelce has much less competition for passes. But make sure your bench can afford a b/u at TE. Most benches seem to be small this year, and you're almost always better off adding depth where you need it most (RB/WR).
Also, what's wrong with Rudolph? He did score a TD in a tough road game (the Rams are elite against TEs) and should have an easier time of it this week. After the elite 3, he's pretty much at the top of most lists in terms of potential.
Personally I would keep Rudolph and use the bench spot for additional depth at RB or WR. Rudolph is at least worth being a #1 fantasy TE in a 10 team league and is in a good situation with Norv Turner at offensive coordinator because Turner has always used his TEs. I'd keep Allen over Kelce.
Someone in my league just dropped Kelce. My starter is Rudolph who's not amazing and my backup is Dwayne Allen. Should I keep Allen or get Kelce?