Personally, if I had to have one bench, I would get a really good solid comp width flat bench.
It's likely to be wider and more solid and take up less room when packed away (usually you can just stand it up making it easy to make room to use a rack for other exercises). That said, the Force USA semi-commercial incline/flat is the closest I've seen to the dimensions of a competition bench. Most are much narrower and taller.
For most people, if you are benching and pressing overhead, incline benching is a bit redundant as it is basically somewhere in between. If you think you need to "hit the chest" more, I find a similar result can be obtained by benching with a back and/or using a closer grip and feet up on the bench or in the air.
An incline/decline bench is great to have, if you have the money and space for an additional bench.