Yeah, ranking the cards is pretty much the second most awesome thing to do ever (after actually playing Dominion)
Some things I don't completely understand/agree with in your list:
1. Masquerade - it's strong, but is it really the strongest card in existence? It draws and trashes, two important things, but it doesn't do either as well as some other cards do. Of course, the combination of doing those things is what makes Masquerade strong, but personally I feel every other card in your top 10 is even better, and even most in your top 20. There are just a LOT of strong cards in Dominion, heh.
14. Young Witch - according to your list, that would be the third best Curser in the game. I don't know, even if it's cheaper than most others the fact that it doesn't increase your net handsize (or benefits you some other way) hurts a lot, and that doesn't even take the Bane into account. I personally think it's one of the weaker cursers, somewhere in the middle of the entire board.
21. Vineyard - Vineyard is nice, but I would be reluctant to place any kind of alt-VP this high on the list since they're all so board-dependent. If it were just a bit easier to get masses of them you might be right, because it is one of the stronger alt-VP cards, but like all Potion cost cards the opportunity cost is rather high, even if you don't have to pay any coins.
23. Borrow - It's a marginal benefit that causes you to have a marginal detriment next turn. Seems pretty mediocre at best.
93. Highway - really? At the very worst it's a Peddler, for which $5 may be a rather high price but it can still be useful in those cases. At best (in an engine with +Buy) it gives you all sorts of explosive megaturns. 93 seems way too low.
127. Herald - Another crazy and underrated engine card. It's probably in my top 10 overall. You only need to see a Herald cascade so many times until you feel that it's absolutely astonishing.
145. Vault - One of the best sifters that has some pretty awesome combos, and is extremely useful in both engines and slogs. Should probably be top 50 imo.
207. Rats - Be honest, has it ever been more than a trap for you? Most of its benefits only work in theory. Probably one of the worst cards in the game, about on par with Scout and the likes.
222. Expand - In most cases it's kind of overpriced, but it certainly shines on some boards, especially if the other trashing is kinda mediocre. Turning Estates into powerful $5 actions is always a nice feeling, and so is turning Curses into Silvers.
250. Counting House - I've already stated more than once that I think it's very underrated, so I won't bother you with the full details again