In chess.com's four-player chess, they evaluate the bishop and rook as an equal 5 points. But the geometry of the board is far more diagonal, perhaps making the bishop actually worth more than the rook. Is there a rough piece value analysis for chess.com's four player chess?
Just like in a normal chess game, it all depends on the positions. In the opening the Bishops are far more valuable than the Rooks because of their additional mobility through the pawns and their range. But if the game reaches the endgame, the Rook becomes stronger because of its pawn-stopping ability. You cannot really assign a precise value to a piece because the value of a piece is always relative to the position and the number values people assign them are just a general guide. That being said, I would argue that the Bishop and the Rook both being valued at 5 is a reasonable estimate of their strengths, but that when deciding whether to take or not you should be considering the positions of the pieces more than anything else. A strong Bishop shouldn't be traded for a passive Rook or vice versa.