I have acrylic everything. I customize everything myself though. You cannot customize glass as easy. I think acrylic is actually a bit cheaper in the mid-sizes (40-200 gallons) and glass is cheaper on the outliers. Heck - my QT tank (20 gallons) is just plastic.
It was really cheap!
The cheap, regular glass has a green tint to it is the color is not as true as acrylic. The expensive glass (Starfire) is more true than acrylic. Acrylic is doomed if scratched on the inside of a live tank because you must buff it out with some polish and you cannot put that chemical into your system, it's also much easier to scratch it. Glass is hardier than acrylic in that respect. Glass has a higher heat capacity than acrylic, so it will conduct heat more readily. This meant you will have great temperature swings, which is something to watch out for.
here is an article at reefkeeping.com:
http://www.reefkeeping.com/issues/2002-03/dw/index.php
disregard the salt talk, since it doesn't pertain to you, the other stuff is still good info though.
IMO, since you are starting, as long as you get a good deal - that's the important thing.
"Advantages of a Glass Aquarium:
Glass aquariums cost less than acrylic aquariums. Because glass aquariums are so common and widely available they normally cost much less than their acrylic counterparts. An All Glass Aquarium 40 gallon breeder aquarium has a cost of approximately $80.00(US) whereas the same size aquarium in acrylic has a cost of approximately $250.00(US).
Glass aquariums are available in many common sizes. In almost any local fish store or pet shop you will find a very large selection of different sized glass aquariums.
Glass aquariums are more resistant to scratches than acrylic. While a glass aquarium can be scratched, it is much harder to scratch a glass aquarium than an acrylic aquarium. You can use a razor blade or abrasive scrapers to clean a glass aquarium whereas the same tools used on an acrylic aquarium would be disastrous.
Disadvantages of a Glass Aquarium:
Glass aquariums are heavy. A 90-gallon glass aquarium has an empty weight of 160 pounds where an acrylic aquarium will weight of approximately 80 pounds. The weights can vary depending upon the thickness of the glass or acrylic used to manufacture the aquarium.
Glass aquariums are more susceptible to leaks and breakage. The seams are more susceptible to leaks because they are bound together with silicone whereas acrylic has a molecular bond, which is said to be five times stronger. An accidental bump with a blunt object or an object thrown into a glass aquarium could be disastrous. Many of the larger, thicker glass aquariums can handle these accidents but can still be broken.
Glass aquariums seams are more visible and susceptible to failure. The seams, where the glass is joined, are more visible and normally have an annoying green tint. Many used aquariums are also susceptible to silicone dry rot. If a used glass aquarium is left empty for a long period of time the silicone which bonds the seams together can dry out and become brittle. Also, if any medication is used, there is a strong chance that the silicone will discolor and take on a blue tint.
Advantages of Acrylic Aquariums:
Acrylic aquariums are available in almost any shape and size. Unlike glass, acrylic aquariums can be made into circular shapes, tube shapes and all of the other common shapes that are not offered in glass.
Acrylic aquariums are visibly clearer than glass aquariums. Glass aquariums, especially thick glass, have a tendency to distort the view of the inhabitants. Most acrylic does not have the common green tint that is normally associated with standard glass aquariums. Acrylic may still have color, and this should be taken in to consideration when purchasing your tank.
Acrylic aquariums are much lighter than glass aquariums. As specified under glass aquarium disadvantages, the weight of an acrylic aquarium is half that of an aquarium made of glass.
Acrylic aquariums are stronger than glass aquariums. Even though an acrylic
aquarium can be broken, they can withstand accidents and mistakes better than glass.
Acrylic aquariums are better insulators than glass. An acrylic aquarium will hold the water temperature easier than a glass aquarium. The ambient room temperature will not have as large of an impact on an acrylic aquarium as it will on a glass aquarium.
Acrylic can be refinished. Unlike glass, if acrylic is scratched, it can be repaired. Kits are available that will allow scratches to be polished out of acrylic. With glass aquariums, once they are scratched, they are scratched for life.
Acrylic aquariums are easier to drill than glass aquariums. While you can purchase drilled glass aquariums, there is always a greater risk of breakage during drilling compared to an acrylic aquarium.
Disadvantages of Acrylic Aquariums:
Acrylic aquariums cost much more than glass aquariums. While the cost of acrylic aquariums have come down one can expect to pay almost double the cost for an acrylic aquarium when compared to glass. Because of manufacturing costs and limited availability the cost is more than glass aquariums.
Acrylic aquariums are less commonly available. Many local fish stores stock only a few sizes of acrylic aquariums, if any. As an example, the LFS near my house has four different sized acrylic aquariums in stock and nearly 30 different sized glass aquariums.
Acrylic aquariums may significantly deform when full of water, causing bowing of the edges and deformation of the sides. Additionally acrylic aquariums need to be supported completely across the bottom; metal stands which support aquariums only on the edges need to have a piece of plywood or other support completely across the bottom of the tank.
Summary
Whether you choose glass or acrylic, as long as you stick to high quality brands with good warranties, you should have many years of enjoyment from your aquarium. I have used glass aquariums since I started in this hobby and have been happy with the results but since I am going to be setting up a 200 plus gallon aquarium, this time, I am going to use acrylic because of the reduced weight and better visual clarity."