For the eastern trains, I'm not sure which one would be tops, in my opinion. If you're going coach, maybe the Capitol Limited would be best, as that's the shorter overnight ride. Other than that, here are my ratings:
Lake Shore Limited: Scenic ride up the Hudson, and, if you get a sleeper, you can hang out in the new Viewliner-2 Diner Lounge. Right now, it's flex food, but the car is very nice. If you go westbound, the 3 PM departure guarantees the view up the Hudson, if you're going eastbound and the train is delayed, you might do that part of the ride in the dark.
Capitol Limited: Nearly all of the scenery crossing the mountains is done in daylight on the eastbound run. If you go westbound, Harpers Ferry will be in daylight, and in the summer, daylight should last up to the crossing of the Alleghenies on the Sand Patch Grade. This train is double decker Superliner equipment. Unfortunately, they're not operating the train with the Sightseer Lounge right now. Hopefully, it will return soon. There is a diner-lounge which provides flex-food dining service for sleeper passengers and cafe food for coach passengers. They let people hang out there, partly, it seems, to compensate for the lack of a Sightseer lounge. I did that on my last trip, and it wasn't too bad.
The Cardinal is the longest and most interesting ride. You get a combination of the Northeast Corridor and the mountain crossing, as well as a ride through the New River Gorge. The eastbound crossing gives you all of the mountain scenery in daylight, and in the summer, it stays light all the way beyond Baltimore (if the train is on time.) During the summer, you get a most of the New River gorge in daylight if the train is running close to schedule. (I once saw a westbound Cardinal pass through the gorge from the overlook at Hawk's nest. This was in August.) The problem with the Cardinal is that the consist is limited -- it usually only has one sleeper, and one Amfleet cafe car that is used as a diner-lounge, with one end reserved for the sleeper passengers, who are served flex food, and the other end for the coach passengers, who have to order off the limited cafe menu.
I've taken the Cardinal a number of times, and I like the ride, but they really need to upgrade the consist and provide additional lounge space for people to be able to get out of their seats during such a long ride. Of course, all the eastern trains need a food service upgrade, and better-quality food needs to be made available to coach passengers. In summary, I guess if I'm going to ride out to Chicago to connect with a western train, I'd probably take the Capitol Limited, as it's the shortest trip for me timewise, even including the connecting ride to/from Baltimore. My second choice might be a sleeper room on the Lakeshore Limited, as I can hang out in the nice Viewliner 2 diner lounge, plus I can wait out the connection in New York at the new fancy Metropolitan Lounge at the Moynihan Train Hall at Penn Station.