This list isn't intended to be taken very seriously. It's subjective, and even where it's not, we're only talking about my personal experience, over a pretty limited amount of time;1 the plant might be completely different for you. Having said that, these are the plants that:
1) have performed well for me for a long time,
2) aren't already common in stores (at least not the stores I visit),
3) typically do well indoors for other people too, as far as I know, and
4) have that special something that makes me want to recommend them to everybody.
This is slightly self-interested, as a few of these are plants I will have available for trade or sale at some point,2 but it's sort of a chicken-and-egg problem. I have them to sell because I like the plant, and in a lot of cases I like the plant because it's easy to reproduce for selling. The main point of the list is not to promote plants because I'll have them for sale, I swear, it's to say nice things about plants that have been making me happy lately. Because there are a lot of plants that don't.3 (Including some of the plants I want to sell or trade away.)
- Aechmea fasciata -- in the trade for a long time, but I rarely see any for sale that aren't already in bloom, and I don't know why. They're perfectly nice foliage plants, and if you buy one already in bloom then it's just going to die on you. (Granted, that can take more than two years, as it did with mine.)
- Araucaria bidwillii -- I know why this isn't sold more in the trade. They're kinda ugly, and even the fuller-looking larger specimens are sharp. I love mine anyway.
- Epiphyllum oxypetalum -- The flowers are pretty, but I'm not sure they're actually worth growing the plant for, since they only last for an evening. I like the plant enough that I'm willing to grow it for the unusual, awkward stems, though.
- Euphorbia trigona -- One of my oldest and best-behaved plants, not counting a minor pest problem when I first got it,4 plus I like the shape.
- Haworthia limifolia var. limifolia -- I started out liking other Haworthias more, but this one's grown on me. The color (metallic gray or gray-green, depending on culture) is neat, the texture is pleasant, and it may be the only Haworthia species I've had that's never given me trouble.
- Pandanus veitchii -- Of course. Minor pest problems (caterpillars or crickets or something, when I had mine outside last summer), painful to move around, and the tips burn if the plant is in the path of a heat vent, but mostly a piece of cake to grow.
- Polyscias scutellaria -- Polyscias in general have been nice to me, though they do have their moods. P. scutellaria is my favorite of the genus because it's been the most responsive to my care so far (bigger leaves, more leaves), but I also like the look of it.
- Senecio rowleyanus -- We went through some rough times at first, mostly because I wasn't watering enough, but we've reached an agreement since then, and it's grown a lot in the last year. Haven't seen flowers yet on my personal plant, but I look forward to the day: they smell like Big Red chewing gum.
1 The plants on the list have all been in my care for at least 22 months; the most recent addition (Zingiber malaysianum) was purchased in June 2009, and the oldest (Gasteraloe x beguinii) is from November 2006.
2 (I've been having trouble getting suitable photos of the plants in question, among other things. Too bright, too dark, always desaturated: it's frustrating. There's also the issue that some of the plants I had hoped to sell are not looking as good now as I had hoped they would, and it's probably too late to whip them into shape, which is demotivating. I spent the bulk of Wednesday taking pictures, and that set is the set I'm going to use, whether they're good or not. I'm currently planning the official unveiling for April 18, but that may be optimistic, given the number of photos I have to sort through.)
3 [shaking fist at sky:] RADERMACHERA!!!!!!!!!! (Actually, I got rid of the Radermachera a couple weeks ago. I'm still angry, though.)
4 It was either whitefly or scale; it happened long enough ago that I don't have any pictures, and don't remember that well. I assumed they were whiteflies, because they flew, but my memory tells me they looked more like immature scale. They went away, whatever they were.