If you dive everything then a BP/W is really the only choice. It’s the best option for adapting to any type of diving.
Horseshoe or donut— really doesn’t matter much. With the donut your bubble can move from side to side when you are head down. With the horseshoe the bubble can only cross at the top of the wing so you will need to either be level or head up. It really is a non-issue since divers who are head down a lot for a reason either aren’t bothered by it or know how to deal with it. I have both types and really don’t notice a difference but most are donut shape these days and all things being equal there is a slight advantage to the donut and that is what I would go with. If you find a really good deal on a horseshoe there wouldn’t be any reason to pass it up.
Aluminum plate is your best all around if you are only getting one. I have steel for cold water and dives I drive to, aluminum for the pool, and if I am flying I have a soft plate (and if I am flying somewhere it will be warm enough I don’t need a bunch of weight). Many will say steel is always best but think about what would be easier—adding weight to aluminum or subtracting weight from steel?