Why everybody hates one brand and will only stick with another i don't know. I personally own a Losi, 2 Traxxas, and my buddy owns a HPI. Now, I think they are all great. Most of the major brands make great products, and each one usually has different vehicles for different applications. For example, Traxxas has the Rustler for a fast, fun, durable beater truck. It has the Revo for an awesome monster for bashing and racing. It has the Summit for crawling and bashing with waterproof electronics. The Slash is one of the most durable trucks on the market, it's waterproof, and it provides super fun scale racing. Losi might have the largest range of vehicles, from it's Mini-T series in the mini scene, to the 8B and 8-T as competitive nitro racing. It has the LST monster trucks for great bashing and great MT racing. There is the XXX series of 1/10th scale buggies and STs for some of the best competitve off-road trucks. HPI has the Savage, a super tough bashing MT that can race a bit too. The Firestorm trucks, they are durable, a little bit race worthy, and fun. It's Hellfire is a great bashing truggy.
If you ask me, they are all great brands and have great products. And it makes me angry when people say a truck is crap because it can't race, when it is meant to be a basher. And I also hate when people say a truck is crap because it's aimed at a certain type of people, for example the noobs who are coming into the hobby. Without these trucks, the hobby would feel a major loss without any new blood in the market.
Just my opinion.
