I'd have to agree with 3db, towers or large mains as opposed to bookshelves, in my experience, offer a larger more expansive soundstage. Unless speaker size is a major concern, I would suggest opting for towers whenever possible for mains.
As for the rest of the configuration, the second most important (or most important for HT/movies) speaker would be your center. This speaker should match the mains as closely as possible. Many speaker manufacturers offer solid center speakers that will timbre match with their mains and bookshelf offerings. As dialogue can typically be 2/3 to 3/4 of a movie soundtrack, this will handle a large portion of work. Take it from experience, don't cheap out on your center, you'll be sorry!
As for your surrounds, these can be anything from direct radiating (most bookshelf/monitor type speakers as well as bipole/dipole type speakers that are specifically made for surround use. Depending upon your listening preference percentage (movies to music), you may prefer one over the other. Another factor in this would be the size of the room and layout you plan on using. Bipole/dipole configurations tend to compensate for a difficult seating layout or broad seating arrangement as they are more diffuse in the soundfield they project If this is not a concern, you may want to consider direct radiating speakers. Mostly movie oriented listeners tend to prefer the bipole/dipole surrounds, whereas those that do a lot of multichannel music listening prefer direct radiating. Both can suit your needs, but you'll have to decide which is best for you.
Lastly, a good subwoofer can make your home theater setup come alive. There are lots of options that range from as little as $200 and go into the thousands, your listening environment and more importantly, your wallet
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, will be some of the major factors for deciding this. Once you've decided your room layout, size and budget, several folks here will be happy to provide you with some guidance on this topic as well.
Speaker suggestions will vary based on your preferences, but from my experience, Boston Acoustics VR3s are a very good solution when looking to get the most for your money (just see my signature!). Axiom M60s, Ascend 340SEs, PSB Image T55s and Onix Rocket RS550 MKIIs to name a few are all main speakers that tend to be very good performers for the money.
3db's advice on auditioning speakers is right on. Whenever and wherever you have the opportunity, listen to both types of configurations and as many models as you can. Several folks here can make suggestions and offer advice, but only you can decide what you prefer.
Good luck and have fun setting up your new home theater!
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