Personally i dont like the decline press, but I love dips. Anything where you are moving you body through space (like dips/pull ups etc...) are amongst the best way to build functional strength. The decline press mimics the dip, but isnt a substitue IMO. The hand position is different, so is the leverage, plus it can be hard on the knees as they are anchoring you to the bench.
Do dips everytime IMO, if you cant do them, then do bench dips and weighted bench dips untill you can
just my 2p worth