Not sure what you mean by the upper three routes, but assuming you mean the TransAm, Lewis & Clark and the Northern Tier, I think the L&C, using the option through Lincoln to Great Falls, and the Northern Tier, will have less climbing than the TransAm. The thing with the Northern Tier, though, is that if you leave from Astoria you climb the North Cascades Highway around the third or fourth day. Here is the profile from the last camping spot on the west slope to the summit of the second pass:https://ridewithgps.com/routes/18434028
Then you basically have a mountain pass each of the next three days. After that, it's relatively tame until Glacier National Park, although the stretch between Libby, MT and Rexford/Eureka, MT is pretty tough (I am planning to ride it again this summer) due to lots of ups and downs along the lake:https://ridewithgps.com/routes/17946093
If you make the foray in Alberta after St. Mary, MT, which I highly recommend, you have a hard, hilly day to get to Waterton Village (great place for a rest day). After that, you have no more mountains, but Magrath, AB back to Cut Bank, MT was tough because of the distance, lack of services and wind.