New bike

Well, the single most important thing about a new bike is fit. So it is a good
idea to go to the best Local Bike Shop (LBS) for your purchase.

If your riding is going to be on pavement, I would recommend a "road bike"
which is often called either a "racing bike" or "10 speed" by the general
public.

If you are interested in performance, then getting a bike equipped with Shimano
105 components is a good idea. You could go more upscale with Ultegra, Dura
Ace or Campy but Shimano 105 has a good blend of durability, performance
without quite emptying the pocketbook.

As to make - the manufacturers: Trek, Raleigh, Cannondale, Giant, Bianchi, etc,
just make the frame. The components: deraillers, rims, hubs, cranks, brakes
and so on are made by component manufacturers. Bikes at the same price point
will often have very similar components. The bikes will be pretty similar in
performance. The different frames will make for slightly different feels in
handling and so on. Also, once you get into the decent components, you will
not find a bike sold with a bad frame. Some bikes will have more advanced
frames and some more generic frames but the frames will always be sound (at
least as far as I have seen).

You may want to get a triple crank (offers more and lower gears for hill
climbing) over a double crank.

Go to your LBS and talk to the nice people and test ride a number of suitable
bikes. Buy the one whose ride and looks you like.