I like Cattleyas because they tend to be more drought tolerant than most and are less likely to die if you occasionally forget to water them. If you are looking for something unusual Prosthechea cochleata is very hardy and blooms a lot.
make sure you check out the cultural requirements, especially the temperature and you need to ensure your conditions comply.
IMHO Phals are the most adapted to the average windowsill grower, but even then you have to be careful of the amount of sunlight they do or don't receive.
I agree with RJSquirrel, attend an orchid society meeting to get some ideas and some inexpensive plants. Some good starters are Onc. Sweet Sugar, Onc. Sherry Baby, Ctna. Why Not. Look for mini-catts that have a reputation for blooming more than once a year.