Most people (including me) will recommend a "normal" focal length for your first lens. A "normal" focal length for 4x5 is considered 135mm to 180mm. A 210mm is considered a long "normal". The 210 is probably your most versatile lens for 4x5. It's a great focal length and most 210's have lots of coverage. They are also dirt cheap right now.
Most landscape photographers prefer a normal focal length and a wide focal length. Some also like a long lens. The 90mm is the most popular wide lens and will fit on your Toyo camera with a flat lens board.
When I bought my Tachihara I purchased a 75mm wide angle because I loved my 25mm Zeiss on my Contax 35mm camera. Three times 25 is 75, right? Well I found the 75mm seemed more like a 20mm to me so I sold it and bought a 90mm which I am very happy with.
Large format is a different animal than 35mm. What you like in 35mm may not be what you like in 4x5. Fortunately, if you buy right used you can resell and get at least most of your money back. I would start with a 135 to 210 lens. Some recommend the 150 over the 135 because of more coverage. Go out and shoot and learn what you like before purchasing any more lenses. After shooting a while you will learn what you like and don't like.