I have been thinking about getting a better 4x5 but one of the concerns I have is limited bellows draw. Off the top of my head the longest available ones are the Ebony and the Canham. Both cameras are pricey though. I learned the other day that Chamonix has a bed extension available and the bellows can handle it. The Chamonix cameras look like the best deal going these days. It is difficult to find anyone saying anything negative about it. With the way the internet is these days that is rare!
I stick with 4x5 because it is the most practical. I used to have an 8x10 but I never really used it unless the image was roadkill. I just never wanted to lug it anywhere. The image quality was phenomenal of course. 4x5 is the largest neg my enlarger (Saunders 4550xl) can handle so to me it is a sweet spot. If all you are going to do is contact print then maybe go with something larger.