About 25 years ago we made our first class C purchase, and honestly, we didn't know much about what to look for. We got lucky and that RV met our needs for over 20 years. We have since replaced it with a new class C, and we knew very specifically what we wanted. It still took a year and a half to decide which to buy. We found we needed to narrow down what we wanted, then go find out what companies built units with those features.
My advice is not to focus first on brand, but floor plans and features. Most of the brands mimic each other in floor plans, but there are a few models here and there with unique layouts. There are a few more upscale brands that can be over double in price, but sometimes you do and sometimes you don't get what you pay for.
Decide first how you are going to use the RV, how many people you need to sleep, what features look important and which do not.
A huge decision to make is what truck chassis you want the motorhome built on, like Ford E-series, Chevy, Ford Transit, Mercedes Benz Sprinter, Doge Ram, Freightliner, etc. Each chassis has weight and size limits. The chassis type will affect cargo capacity, overall length limit, towing ability, etc. I'm going to say the most common class C RV chassis currently is the Ford E-450. For small units under 25 feet, the Sprinter is popular. Motorhome magazine had a good article, although it's a couple years old, explaining pros and cons of the chassis choices. Note that some of them in the article are for class A only. https://www.motorhome.com/tech/motor...is-connection/
You need to realize that RV build quality and reliability is generally very poor, compared to modern automobiles and other large consumer products. I can't think of another large consumer product with such bad quality. You can look on line for various brand quality ratings. Realize that even within the best brands there may be lemons, and among the worst brands there could be some trouble free RVs. https://www.rvt.com/blog/trends/rv-m...s-and-reviews/
Buying a motorhome is a big purchase. I suggest spending 6 months to a year shopping until you fully understand your needs vs what's out there.