so yeah, i've changed my opinion on this quite a bit in recent weeks
08 was my worst pick on that list, hands down. it's not nearly as good of a starting plant as i thought, as you will miss out on big plants in turn 2. if the plants on the market suggest things may open up in turn 3 rather than 2, 08 becomes the best starting plant...but that's not too common and very difficult to predict in advance. there are times when 09 is the better choice as a starting plant!
20 shouldn't even be close to the top 10, at least in 3-4 player. strong games will have some players who focus on efficiency and others who will aggressively attack coal & oil, making those resources dangerous toward the end of the game. this means you will have your prices driven up from an early point, and you will be badly behind on money compared to some others. it is much better in 5-6 player with the higher restock rates and increased emphasis on building capacity early, but then again the 4-cap plants become much more viable endgame options in those games too...
38 is debatable in 3-4 player. good players will go for the 24 if it's there when trash gets down to $4-5, and 30 will always be bought if it shows up after the first few turns. trash is less safe than in average games when this happens, but it's often still less scarce than coal or oil by that point. on many occasions, 38 will be the only viable 7-cap plant for players at the top of the turn order, so there is an argument for keeping it on there.
39 actually has a case for similar reasons as the 38, as most of the 6+ capacity plants in step 3 are coal & oil-guzzlers. it's usually cheaper overall than the 50, even for 2 turns, and is obviously much better for turn order.
30 is not top 3 for the reasons mentioned before, but still top 10 overall. there will be games when this plant singlehandedly wins the game for the person who can pay $90 for it and still afford resources. its peak value is much higher than that of the 25 or 26, but those plants are much more consistently strong. i actually think 35 has the highest peak value of any plant period if it comes out early, but that's so rare that i can't in good conscience rank that plant in the top 10.
03 should definitely be on there. gives you great building position and can get you the prime spot to fish for a big plant early on. it also holds up better than the 04 if you have to run it for more than a couple turns (i.e. something like 03 + 13 or 03 + 10).
32 is another plant that's turned out to be significantly worse than i thought, as oil gets attacked much more in good games. coal is still much worse as the game goes on, so this is borderline top 10 in 3-4 player. not the most efficient, but sometimes you just need capacity before step 3 and you can generally store extra oil on this in preparation for the end.
21 becomes kinda weak if it doesn't appear until the middle of the game, but it's so good in the early stages that it still belongs up here. if you plan on replacing it at the end, it's also a fantastic storage plant that can allow you to safely buy something like 40 or 42.
28 & 29 were hands down my biggest omissions from my previous list. among the usual pre-step 3 plants, these two make far more money per turn than anything else besides 25/26 (and even that often doesn't hold up toward the end). this makes them tremendously underrated for 3-4 player, where money is crucial. they are also possibly top 5 overall plants in 6-player, as you can reach endgame capacity in many more ways here with a 4 plant (4-4-6 & 4-5-5 are both realistic). building out for an early win at less than endgame capacity is also much easier in 6P than in smaller games, and these plants give you the money and capacity you'll need to pull this off. 28 & 29 are my two favorite plants in the game now, for real.
so let me try this again...assuming 3-4 player on USA/germany style maps:
26
25
29
28
04
03
21 (for early-game value)
30 (#1 in games with no 24 until late or major coal + oil squeezes)
32
38 (giving this the nod over 39 since a generally-safe 7-cap plant is far more unique)
really though, all a list like this can do is give you a rough idea of the plants that win games most often. this game is so much about situational value that i don't see a point in going farther than this (by, say, making a tier list of all the plants). quite often, the 36 will be a game-winner for the player at the bottom of the turn order and untouchable for anyone else since they risk having coal bought out - does this make it a top-tier plant or a low-tier one? the answer, of course, is neither, as the concept of fixed rankings does not work for this game!
i think the most worthwhile project in this fashion would be something akin to the twilight struggle strategy site: writing an individual article on each plant which discusses its uses in the various situations you will encounter in real games.