You also need to state whether or not you want the satellite reception to work while moving or stationary only, and if the install is to be "permanent and integrated into the cab structure" (like on tour buses), or semi-transportable. I'm guessing you're considering the standard satellite dish type setup requiring setup at every stop? The smaller the dish, the more difficult the pointing is and the more signal loss you'll get with thick clouds and rain/hail.
Reception? It's perfect, digital sweetness if you are on the signal from your provider (Dish, Direct, or Bell.) There is no difference on "reception" between the choices of brand. The actual choice to be made is how and where you will mount the antenna. Another deciding factor is if you want HiDef service or not. (DirectTV does not do HD on 18" round technology)
4 methods for satellite:
1. An 18" round dish. Put it on a pole or stand, a load-lock pole mount, or mirror clamp-on mount. You point it outside the truck by hand. Advantage: cheapest Disadvantage: must get it up high enough to not get blocked by other trucks. Must point it my hand and this takes some technique, especially in bad weather. Have to put it up and down every night. Can get blown more easily off signal in a stiff wind.
2. A Tailgator, Flex, Pathway, Carryout. Set it outside and turn on the DirectTV (Flex) or Dish Network (Tailgator) box inside your truck and it will find the signal. Advantage: portable and weather proof. It finds the signal on its own. Can be mounted using a variety of methods, like a magnet plate, window mount, load-lock mount, or mirror mount. Disadvantage: you still have to get it high enough to not be blocked by another truck, etc. You have to put it out at night and store it somewhere while moving. They can be hard-mounted, but it voids the warranty.
3. VuQube. Mount it to the back of the truck. Find the signal using remote control from inside the truck. Advantage: nothing to get out and put up. If mounted high enough, cannot be blocked by other trucks or obstructions. No other cable or power needed besides the coax coming from the back of your satellite box. Disadvantage: takes moderate amount skill or a knowledgeable shop to install it correctly. If you don't own the truck, your company may have a rule about mounting things on the truck. Takes little bit of understanding of where the satellites are and how to point it.
4. DuraSat. Mount it to the back of the truck. Get it up high enough and everything else is automatic. Advantage: It finds the signal with the press of the button. "In-motion" option even stays on it while driving if you have a partner in the truck who wants to watch TV. Disadvantage: most expensive of these options. Need to connect one coax plus a two-wire power connection to the truck 12-volt system. Takes a skilled installer to put in on correctly. If you don't own the truck, your company may have a rule about mounting things on the truck.
Here is a picture of many of the above mentioned stuff.