Prize Goat's trashing is nice but not that big of a deal, on average by the time you have more than a couple loots the game should be ending in like.. maybe 6-7 or so more turns? Give or take. So you'll play your early-ish Prize Goat maybe 3 times or so. Personally I don't think I've had a game yet where I play Prize Goat and trash more than twice--not saying getting more trashing benefit doesn't happen and that it might decide the game in some cases, for instance maybe heavy cursing with Haunted Woods and no other trashing, but it's far from typical for this to be the case.
The issue isn't specific Loots always being good or better than others, that's the wrong way to look at it -- it's getting the right one at the right time that's most helpful in that kingdom drawing it as reliable payload.
Loots aren't super powerful, but they are good enough (better than Gold) that you want some and yet they are also stop cards so if you don't build a reliable enough engine while also going for just the right amount of loots (and hopefully ones that are useful with the board), you end up significantly behind. And the fact that they usually have +buy or a gain makes for some rather unpredictable three-piling as well.
Part of this may be our inexperience with the new set's cards and the fact that Preview games are heavier on loot-using cards than will be the case in full random, but I'm seeing a lot of games with loot where one person gets 5+ loots and buys 3 provinces on consecutive turns (i.e. 6 provinces across 2 turns) when the other player has barely started greening yet, maybe has 2 loots and afforded a province or two. This happens all the time, a wide disparity in outcome that I just don't see as often in normal games and also don't see in Preview games that don't include loot.
Like I was saying we'll have to wait until the entire set has been out a bit and people are used to the new cards and mechanics, but my early take is that games with loot are disparate in their outcomes and basically Boon/Hexes on steroids in the extra unpredictable randomness they introduce, though of course they also add for interesting mechanics and unique abilities in a Black Market-esque way, just unfortunately not allowing for any of the same skill in adapting to them.
If there was a variant of Dominion geared towards more expert players with, say, two changes:
1) Loots, Boons, Hexes, and everything that refers to or uses them are removed from the game (except maybe Druid and its 3 random setup boons)
2) There's an even, 50/50 chance of Black Market being in the kingdom or not.
.. that would probably make for universally better games, at least for dominion.games rated players in the range of, uh, 55+
