Which Polsilvers are generally considered the best? I know YMMV, but in general..
There's only one Polsilver; it isn't a brand. In fact, it's another Gillette blade, made in the same factory as Yellows, Nacets, Silver Blues, etc. The only reason it costs much more than those is because there are rumors that it will be discontinued (the rumors have been out there since 2013), so people horde them, which drives up the prices.
There are some older versions, made in Poland at first (hence "POL silver") said to be even better. Here's my enormous stash of these coveted vintage blades:
Personally I can't tell a difference between these and the new Russian ones. A Polsilver is a polsilver is a polsilver