Granted there are alot of well informed posts here, obviously from professionals in the business.
As previously stated many customers refer to a "Toro" system or Hunter or whatever. I explain to them in person and state in the contract that we use materials from several different manufacturers to give the you best possible system installed. If they're still adamant about a certain manufacturer I'll heed to their requests.
Below is my preferred manufacturer's materials, and more importantly, WHY ! Items are listed in order of preference. Granted there may be some hair-raising things below to some contractors but just remember, respect my opinion as others respect yours:
Rotary - Toro Super 800 [5"&12"x3/4"] and Mini 8's [4"x1/2"], Hunter PGJ [12"x1/2"] alternatives to these are Hunter PGM, RB 3000-5000 series. Stay away from Nelson, Hardie, Irritrol, Weathermatic, Orbit, Buckner. First thing wrong here is the gears and adjustments don't last or they're just plain "cheap crap".
Fixed Spray - generally all fixed spray perform the same. What you want here is versatility and well made material.
I prefer the Toro 570 series [all sizes] with VAN nozzles. Hunter PS / SRS series and RainBird 1800's are good too. All three have adjustable nozzles and have either a check valve installed or available. These brands are also a thicker [or better] grade plastic casing and riser and are sealed well at tops.
Valves - Toro EZ-Flow series with flow control and solvent weld fittings. Solvent weld until you get to 1 1/2" and higher, then threaded. Don't forget to seal with pipe dope.
Valve Boxes - Whatever your preference here is fine as long as you DON'T use the Economy or cheaper models available. Get heavy duty. They're worth the extra buck and a half. One look at both will show you why. One you can park a truck on top of, the other you can't. Need I say more here ?
Fittings - Generally most distributors carry Lasco fittings or something comparable. As stated previously, stay AWAY from the Home Depot stuff.
Pipe - Cresline is usually the brand name most prevalent out there. Whatever the name make sure they manufacture "virgin" vinyl and not recycled for all of your PVC products. Poly pipe, Cresline again is the manufacturer of choice.
Wire - A standard multi strand irrigation wire usually 18 gauge is sufficient for most residential and commercial jobs. Larger jobs would buck the wire up to single [solid] strand 16-14 gauge.
Controller - My controller of choice is the Hardie Rain-Dial or Total Control. Toro has also matched these two controllers with there name on them and "beefed up" the resistors and capacitors in them and thus charge a bit more for them. These controllers handle electrical problems better than others [hence, dirty electric, surges, lightning strikes, etc.] I prefer these first also because they are VERY simple to operate for a homeowner. Granted all controllers work the same but some are more difficult than others to program and use, especially for homeowners. The Hunter Pro-C, SRC and ICC models are good too. I prefer to stay away from Rain-Bird contollers.
Rain Gauge - Rain-Clik is pretty much the standard. Granted each manufacturer makes the equivalent and says "their's is better because ...".
Personally unless the customer says at the beginning that they're out of town alot, I don't push them. They're tinkertoys and a maintenance headache. Granted you may be able to charge for a service call but I've usually got bigger fish to fry. I don't recommend them. The old rule of thumb is watch the weather report and go turn controller off if it starts raining. Turn back on when done or accordingly.
As stated previously, these are my recommendations and of course are subject to opinion. But all the other stuff I wouldn't give you a red cent for a caseful of whatever.
Remember, tell your customer that whatever they plan to buy [system] that once it's installed, IT'S INSTALLED AND DONE ! IN THE GROUND and it'll cost more to repair. Repairs on a crappy install are forever and never ending. Granted I love following around the "crappy" contractors. They can keep right on installing. All it does is increase my service calls, fatten my wallet, increase my reputation and customer base.
The GOLDEN RULE OF IRRIGATION IS THIS:
A system installed or repaired is 95% good design and craftmanship and 5% good materials. That's it.