+1 for what HollyBoni said. If you're seriously thinking you need more than 700x45 you might want to start looking at something like the Fargo Ti (ie. drop bar mtb). As the tire gets taller the trail (steering/handling) changes. Similarly if the bike is optimized around a 700x60 (29er) then the handling might not be what you want if you go to a 45 or 43.
We have a Fargo with fast 2.2 MTB tires and love it, but our Sutra Ltd. is fine with 50 mm tires it came with. I've tried them both with smaller tires. Maybe it's not possible for the OP here to try before you buy but that would be most important for me. Delaying gratification and trying bikes has made the purchase decision easy and the bikes have been satisfying that way.