i am going to buy a trek or a felt bike under $1600 what should get?

More important than brand is how the bicycles geometry and size fits your size and style of riding. I want to touch on the first part of that. Many bicycles sold under different brand names, are actually built and assembled by a small number of factories. In fact many competing brands will offer identical bikes, and the only difference is in the decals. They were made in the same place, using the same materials, and built by the same workers. Some of these factories have license to produce components under popular names, and often different name-brand items are actually made on the same CNC machines.

Whats more important is fit. Frame geometry, frame size, top tube length, seat tube length, stem size and rise, crank arm length and Q-factor. The simple answer is ride both bikes before you decide.

However, I'd like to make a suggestion. A $1600 bike is not the bike to learn what your preferred angles and measurements should be. That's an expensive lesson. I'd suggest buying a more basic road bike to be your "discovery" bike, something in the $600 range. Learn about proper frame measurement and how angles affect the ride before you buy it. Find out why stem length, handle bar width and crank arm length all make a difference, and then spend some money buying and trying the different size components to see what feels better to you.

Proper fit is a complex process, but when you know what angles and particular measurements are right for you, then making a bicycle choice will be simple. It will be the bike with the right numbers, not the right decals.