I have one of each of the three LC+ steamers, and a diesel on order.
First, I think that the Mikado is the best value of the three available steamers as its level of detail is slightly greater than the Hudson and Pacific. The boiler piping stands out a bit better, and the rods and running gear are more complex and detailed.
The speed control on the LC+ locos is superb, amazing at this price point. The fan-driven smoke is outstanding and prodigious.
Each of the three LC+ steamers has a different whistle sound. The chuffing is excellent and synchronized with the fan-driven smoke puffs, which is another advanced feature that is wonderful to see at this price point. The quality of the sounds is not the highest - but very good. I have no complaints or dissatisfaction on this point, I just point this out for completeness.
To my eyes, the Mikado does not look small, as there were plenty of small mikes built at different times. I see the compression more in the Hudson and Pacific - the three locos are about the same length, which compresses the Mikado less that the others, at least to my eyes.
The Mikado cannot be close-coupled as the Hudson and Pacific can be by adjusting the mounting hole for the drawbar (see other posts on this).
Overall, I think that the Mikado is the best value based on its slightly finer details, and to my eyes (no measurements), lesser scale compression. But my favorite of the three is the Hudson because of the overall more massive look, and the close coupling option is tighter on this loco than the Pacific, again, adding to the look of power and mass.
On the LC+ steamers, I also note and agree as others have, that since there is no front coupler, the control placement of the whistle could switch to allow better whistle control without accidentally uncoupling. I also think that Lionel needs to release LC+ diesels without the "sturdy stamped metal handrails". I am hoping that the FT will be released with LC+ for that reason.
-Ken