Well my MTB experience is limited, but for what it’s worth:
I began back in high school riding full suspension, but Walmart Mongooses. Now I ride an entry level Specialized hardtail. The ride was much smoother on the Mongoose…for the 3 months it lasted before I tore up the cheap components. Once the bike was torn up, it was years before getting back into it. But I can definitely say I enjoy the Specialized a lot more despite the rougher ride. Maybe it’s the 29" wheels or maybe it’s having a bike that can take some abuse, aside from the cheap fork. But overall, if it were me, I’d keep the current bike maintained and save for a good FS.