I have tested countless dressings, and 303 is my favorite. Vinylx is a distant second, and third place has to go to Black Magic Semi Gloss, which I use on most customer cars. Besides the UV protection and factory sheen, 303 offers limited dust attraction. In my car, I notice ZERO dust attraction, unlike I notice when I use Vinylx or, God forbid, especially Armor All (even the matte finish kind, though not as much). I can't stand having to wipe down my interior every other day, but with 303, I get no dust so I don't have to. On cars with huge dash boards, like a Lexus RX300 that I detail, dust attraction is imminent, no matter what dressing is used, but what I have noticed with 303 on an RX300 dash is that it takes much longer (several weeks) for dust build up to become visible. With other products, dust is visible the next day. 303 is durable, so a pricey bottle of 303 lasts me a long time. It has no smell, unless you take a whiff of the inside of the bottle.
Nothing has a better matte sheen than 303, and nothing attracts as little dust as it. I will always use it on my dash.
As for Black Magic Semi-Gloss, which was mentioned earlier in this thread, it's ok stuff. The gloss is less sheen than even 303, and you really need to apply it thick to notice any difference at all. It smells strongly of citrus, but it goes on uniformly and it's cheap. Dust attraction is also very limited, but not quite as limited as 303. So if you want a cheap 303, BM Semi-Gloss could be a good alternative. But if you want the best for your car and the easiest on you, there is no subsitute for 303.