Well from a performance point of view, most professional prime focus dishes are three axis dishes. Azimuth, elevation and skew(polarity adjust). Orthomode feeds were intended for these three axis dishes, so they still had skew control. For 99% of viewing the skewing of a polar mount dish is sufficient and a polar rotor is unneeded. Orthomode feeds give you the advantage of more than one receiver. But cost twice as much for LNBs. You can buy LNBs from less than a hundred to well over six hundred each. The difference may be unnoticeable when paired with less expensive receivers and such. I have a Dual orthomode feed, Bullseye II, with four expensive Norsat PLL LNBs on a 10' dish. They require an external power source for the receiver is unable to provide the current needed. Retail on that feed and LNB setup would be about $1800. Is it worth the money? Considering I had no special needs for high priced equipment, probably not.
I single LNB feed with polarrotor does not have to freeze in winter. That's what the covers are for. They can give you very close if not the same performance with the same LNB as an ortho. You don't need to spend a lot of money for good performance. But to try and define "the best" is subjective. I would look more to how do I want to use my setup? As a guide to your purchases.
