For pre-built units, you should shop for Bluetti, EcoFlow, Pecron, and Anker. They each have slightly different feature sets and each manufacturer has sales on one or more of their units all the time. Pick which ones have the features you most like and keep an eye out for sales. I managed to score one of the Pecron E1500LFP units on a really good Black Friday deal and like it a lot. My only complaint is that their app doesn't let me dial back the charging current. I like doing that because it increases the longevity of the batteries. The EcoFlow unit and its app lets me do that. Also, if you plan to use solar panels, check what your power usage will be vs the amount of solar power the units will accept. If you're planning to use 800W and the unit only accepts 200W of solar input, you're going to have a hard time keeping the battery charged up.
Solar panels seem to have a similar bent. I've gotten Dokio, AllPowers, and a couple others I can't remember. Each manufacturer has a lineup of different wattage units. And, they too have rotating sales on specific panels in their lineup. The most recent one I got was an AllPowers 600W folding unit. It's pretty big but actually a lot lighter than 400W units I've seen and is about the same weight as the 300W Dokio I bought a year or so ago. Note that connectors are something you need to keep an eye on as well. Some power stations like MC4, some like XT60, some like Anderson Powerpoles.
As for building your own setup, I haven't done a lot of that but what I have done has been with Renogy components. Pricey but they seem to just work without a lot of painful setup/configuration crap. I stopped buying their LiFePO4 batteries because there are much, much less expensive equivalent batteries available now with decent quality.