Here are my top five (note that these pictures are for reference. They are not pics of my plants - mine are more beautiful):
Bollea violacea (maxillaria/zygopetalum alliance)
Easy, easy, easy. It takes a while to get established, but once it does, it grows like a weed. I grow it under phal conditions and it does just fine. The only major things to worry about with this plant are light intensity and water frequency. Though it can take some morning sun, the leaves scorch in light that is too bright. Also, the plant doesn't have pseudobulbs, so you have to be vigilant about watering. However, it's pretty tolerant of a wide temperature range and, as I said before, it is pretty hardy once acclimatized. This one's usually a summer or fall bloomer
Vanda brunnea (vanda alliance)
I've found most vandas to be prissy, unforgiving plants that fail to bloom and grow if you make even the smallest mistake. Not this one. This is an ironclad of a plant that, as long as you water it well, will thrive with gusto. Anyway, it's standard vanda culture for this one - bright light and heavy watering. I've heard that it's a spring bloomer, but mine blooms later.
Pescatorea klabochorum (maxillaria/zygopetalum alliance)
Probably the easiest pescatorea to grow - "Ironclad" is a very fitting description of this plant. What's neat about it is that the foliage looks great even when it is out of bloom. The foliage consists of a bunch of leafy fans that clump together, making the plant resemble a robust daylily. And the flowers? Well, just look at the picture, and you'll see why it's one of my favorite plants.
These guys can also be grown in phal conditions (I.E. Warm, shady, and moist). They're less touchy about new conditions than are some other pescatoreas, and are much quicker to acclimatize. They seem to grow faster when they're exposed to some air circulation. However, like other pescatoreas and like the bolleas, they need to stay moist because they don't have pseudobulbs to hold moisture. This one usually blooms in the fall for me.
Pescatorea cerina (maxillaria/zygopetalum alliance)
Another tough-as-nails pescatorea - tolerant of less than perfect conditions and fairly fast growing (given good watering). Mine came to me in poor condition and bounced into life in only a matter of time. I grow it as I do my other pescatoreas and bolleas (see above), and it grows like a weed. Anyway, this is another fan-shaped plant, with fairly short and sout leaves. This particular pescatorea has yellow and white flowers (though I've seen some plants that have pure butter-yellow flowers). I think the flowers are cute (they remind me peeps marshmallows, the ones that are shaped like chicks). I've yet to flower this one, but it's doing so well that it'll probably bloom in no time.
Dendrobium Burana Stripe (dendrobium alliance)
Good ol' reliable. My very first orchid was one of these guys, and it continues to bloom for me year after year, no matter what I do to it. Every fall, I anxiously wait for the spikes to emerge and, surely enough, they do. The show only gets better as the plant gets older. The first time I got it to bloom, it put out one spike with five flowers. Last year, it put out four spikes, the longest with twelve flowers and the shortest with four. I'd really recommend this one to newbies because it's very forgiving about less-than-perfect culture.
I grow it in catt conditions and it absolutely thrives. The only pet peeve I have about this plant is the fact that it grows very slowly. It only puts out one new cane each summer and doesn't finish maturing it until late in the fall.