Gladiator does offer a pretty large assortment of different products versus other brands. The RTA tries to appeal to a more casual crowd, people that move a lot, or are looking for something at a lower price-point, while the Premier product line is "supposed" to be for a more rugged crowd that want a little more survivability.
Cosmetically, from what I've read some may see the pseudo-diamond plate design scheme as cool, where others see it as trying too hard.
Functionally, it is really about what you intend to do with Gladiator pieces. If you want maximum performance in this price-point / intended use category the competition within the same class does make a damn good argument to buy their stuff. Some of the design choices Gladiator made left me scratching my head, while some I thought were really innovative and even fun.
Price-point swings wildly depending on where you shop and when. Gladiator at times seems a little "proud" of their product line and that seems to translate into a higher premium for what some of their pieces can actually do/offer versus others. Owning a majority of what is in the Gladiator library, I can say that there are times when I felt the premium put on the Premier brand was justified and others where I thought it wasn't.
The probability for RTA / "non-Premier" products having damage bad enough to warrant part replacement due to significant damage or parts completely missing, in my household, was ~33%. The sample size was 15 pieces.
The probability for Premier products having damage bad enough to warrant part replacement due to significant damage or parts completely missing, in my household, was ~25%. The sample size was 12 pieces.
Despite having a Sears, Home Depot, & Lowes in our area, those stores only had a small representative sample of what Gladiator offers and what was available between them was fairly comparable. Should you want to order something you can't see or touch you'll have to rely on reviews or forums to get an idea of how a product performs.
If you watch some of the videos I uploaded on YouTube you'll see that there are some products my wife and I really liked and a few others that were a little "eh." Overall, our impression is pretty neutral, but that doesn't mean we didn't have some significant issues with Gladiator, which thankfully were amended.
It wouldn't say its a starter brand by any means (i.e. cheaper plastic or MDF products). They do the job respectably, but Gladiator isn't a rough and tumble survive pretty much anything you throw at it brand. It is more of a jack of all trades master of none in this price-point/use category.
When my wife and I find a permanent residence, I'll retire my Gladiator stuff to my man-cave. I think they'd be great for that!