I'm a beginner bike rider (Haven't riden a bike in 10 years). I am planning on riding about 8 miles a day back and forth to work. I'am a 32 yr old male looking to get some physical activity into my life. Since I am a beginner, I am looking for a road bike on a budget ($300-500), with an ambition to upgrade in future if I end up liking it. After some online research and visiting a couple shops I am down to two choices:
1. Giant Escape 3 giant-bicycles.com/us/escape-3-2016 $360
2. Trek fx 2 trekbikes.com/us/en_US/bikes/city-bikes/fitness-bikes/fx/fx-2/p/1323010-2017/ $520

Both have good reviews and is good for beginners. I rode both and felt the Trek to be smoother in terms of gear ****ing, lighter and better gripping handles. That being said, Giant was not bad by any means. I just felt a bit more smoother with Trek.

Should I spend the extra 160 bucks and get the trek bike or save the money and stick with Giant? Advise please.

The Giant has a freewheel hub, which is a poorer design than the 8-speed cassette hub on the Trek.
For utility riding, get a utility minded bike. Apart from gears, to me that means fenders and a rack.

Me, I'd look for a disc brake bike for a commuter. Better performance in rain, takes less hand effort. If you keep adding mileage, your rims last longer.

Don't buy a bike with upgrades already in mind.
Bike parts are a lot more expensive when bought piecemeal than when bought bolted to a bike.
A thorough upgrade at shop prices will cost considerably more than buying the bike you want in the first place.
A better option if you want to start "cheap" is to go for a second bike. Your first bike becomes the rain, or the backup bike. Maybe even the winter bike if you live someplace where winter actually means something.

Welcome to Bike Forums geny.anthony.
As this is the Introductions forum, where you are supposed to only introduce yourself, you aren't likely to get many answers here. I suggest posting your questions in our General Cycling forum. General Cycling Discussion - Bike Forums

Hi geny, welcome to the forum. Since you are a beginner it probably doesn't make a lot of difference, but if you are serious about riding, I would suggest you get the more expensive one, it will be a better bike. I think we need to look ahead and consider the psychology of a new rider. It's more than likely that being your first bike you'll come to love it and want to hang onto it, ride it into the ground basically. I know I did and I know others who still have and ride their first. In a years time or 2 that extra few hundred dollars will seem like nothing but the pleasure of having a bike of higher quality will never leave you. Good luck either way.