If you don't have any previous o gauge trains that are conventional, then by all means, get the Lionchief Polar Express set! It has better sounds like chuffing, whistle, and bell, plus tom hanks announcements all from the palm of your hand. It has better smoke (fan driven) vs. old fashion puffer which is just cute little o-rings compare to nice strong puffs. It has a stronger/brighter front headlight. Lastly its easier to use. Just plug in the wall wart that connects to the track and hand the remote to any child of any age.
It also has cruise control. No slowing down around curves and grades going up, or racing down the down grades.
In the future if you get a different engine in the future, just add it to your track, and you have two locomotives on the same track controlled by two different remotes assuming you have the running space to run two trains on the same track.
Should the O gauge bug really bite you hard, and you invest in MTH DCS locomotives and command system along with Lionel Legacy or TMCC, you can still place that loco on your world class high rail layout and run your polar express with your remote.
If you take it to someone's house that has conventional only, and you want to run only your Polar Express, you can do that by putting the old conventional transformer to full throttle (18v), and controling it with your remote. You just can't run your train at the same time with a conventional locomotive because you would not be able to control the conventional train and the high voltage would probably make it fly off the tracks.
If you plan on buying and running older post war trains, then you may want to consider the CW80 version and forgo all the above, but I think the plusses of Lionchief are well worth it IMHO.