I had soft saddlebags, used them for exactly three trips before shelving them. They're not secure, they're a pain to put on and off, scratch the paint, and they don't even hold that much (mine were 30L each, but they're all oddly shaped).
Next step was a 60L duffle, which actually worked phenomenally well. It's a huge convenience having only one bag (two with tank bag) to take on and off the bike. The one large storage area allows maximum storage for the space available.
Next came a Givi E52 top case, the single best luggage purchase I've ever done. It's big (don't go small, you look like a dork regardless), waterproof, and secure. It never leaves the bike, though it's a 5 second step to remove it. There's a reason why top cases are the defacto luggage solution outside of north america.
Next came Givi V35's paired with the E52. The V35's can store a fair bit, better if it's all squishable stuff, hard items end up taking a lot of space due to the shape of the V35's. Easy to put on and take off. And if there's a PLXR rack available for your bike, you can even take the rack off.
For all hard luggage, the cheapest option is to buy the bags used and unless you get luck finding a used rack, just get one new. My E52 cost me $150, and the V35's were $300. From memory, the top case rack was about $150 and the V35 racks around $200. For the luggage, I just messaged everyone selling a bike with bags to see if they would part them until I got lucky.
Bottom line... Cheapest good option is a duffle bag strapped to the back seat. More expensive is a top case. Only after you have a top case would I get the V35's. The top case plus duffle is my ideal luggage setup. Everything else ends up weighing too much. Remember, the more space you have, the more stuff you'll bring. More stuff equals more weight, making the bike handle like a pig.