Yes, HDDs are slower than SSDs. If that axis matters to you, you'd use an SSD, particularly NVMe. (Which is sort of implied by the hybrid setup I suggest.) If storage capacity matters, HDDs. You can see this reflected in market prices, though it does look like SSDs are surprisingly cheap these days, comparatively. Historically this has not been the case. (I wonder if economies of scale are now working against HDDs suddenly, or what? There's no reason for them to cost the same or more than an SSD — the market would collapse. Although I swear market pricing for many components hasn't made a lot of sense, recently… i.e., RAM has seemed horrendously expensive.)
There's some sort of big SSD price drop in the past 3 months. I dunno what that's about, but I did upgrade a machine, so that's nice.
There does definitely seem to be a pricing mechanic in that hard drives never really scaled down in minimum unit cost; the basic parts of a hard drive still cost real money, so if you can do 2TB per platter, and a top of the line drive has 10 platters, a single platter 2TB drive costs a lot more than 10% of the top of the line drive. OTOH, flash controllers aren't that expensive and/or the cost of the controller scales with the capacity, so SSD prices tend to be more linear with capacity.
If you need a lot of space, $/B means a lot, but if you just need an ample amount of space, $/device is more important, and SSD drives have hit the point where an ample amount of space is available for less than any hard drive.
Yes, HDDs are slower than SSDs. If that axis matters to you, you'd use an SSD, particularly NVMe. (Which is sort of implied by the hybrid setup I suggest.) If storage capacity matters, HDDs. You can see this reflected in market prices, though it does look like SSDs are surprisingly cheap these days, comparatively. Historically this has not been the case. (I wonder if economies of scale are now working against HDDs suddenly, or what? There's no reason for them to cost the same or more than an SSD — the market would collapse. Although I swear market pricing for many components hasn't made a lot of sense, recently… i.e., RAM has seemed horrendously expensive.)