Like, a bike, everyone has their favorite. Around our place we take bbq'ing quite seriously. Yes, I'm the guy when its -40 below at canadian tire getting a tank refill in january. We use a napolean 3 burner grill w/ rotisserie back burner, entire top is cast iron. Paid a good chunk more than the chinease stuff about $500, it has been stellar. Some things to look for regardless of what brand you buy:
1.) Cast iron heat grates - hold heat much better than stainless steel, takes longer to heat, but gives a more even heat, doesn't sear the exterior of the meat when it touches the grill @ 250-300 F
2.) rotisserie is absolutely awesome, paid a bit extra for the napolean brand one (don't know where its made), but seems to work better than the junk at CT (seen 2 of those fail). If it had an odometer, it would be on its second lap around.
3.) Get grill grates that are non-linear, i.e. wavy, curved, saves small stuff like asparagus from falling through the grates
4.) starter has been excellent after 5 years of rigorous use
5.) pivot point of the lid, your going to have to lift this up and down a lot over the life of the bbq, many of the cheaper brands do not balance the lid making it heavy or causing it to warp when lifted (if its not cast iron)
6.) buy the size you actually need, while massive grills look cool, they take forever to heat and use a lot more propane. Also get 2 tanks, so your never out
Best is to plumb it straight into your natural gas, but doing so can be $$ or a hassle.