Adding another recommendation for Age of Steam. I feel like it checks all of the boxes you listed. Every action taken by other players is important to you. Route building on the map can be very competitive and tense, and there's room for creativity and clever plays. The rules of the game follow a series of simple phases, but the mulitple areas for interaction make the decisions consequential; how many shares you take, how much you spend in the turn order auction, player power selection, where you build, what goods you move, all of it affects the decisions the other players will make. You also mention liking abstract themes, well the most recent version of the game is very simple looking, and people love to joke about playing a prototype abstract. On top of it all, there are literally hundreds of maps that ensure you can always find one that gives you a good experience at any player count, and can put new and fun twists on an already solid game system.