My two cents on sanders in general maybe you can extrapolate something that helps you
RO 150 FEQ-->Large surface workhorse
This has been my goto workhorse (use it for 80% of my job due to time savings) for large surface projects that don't require an absolutely exquisite finish. If I follow my grits from a stronger grit all the way down to the finer grits and follow with the sheepskin grit, I can make a piece of wood SHINE without even applying a finish with this sander. So no scratch patterns if you can go fine enough in grit (but sometimes you can't go that fine in grit because you can't apply finishes as effectively if you go down to fine on your grits---i.e. the need for a finer finish sander that can get less scratch pattern at a higher grit).
Gets most of your sanding done on large pieces FAST (which is why it is my goto workhorse).
RS 2 E-->Large FLAT surface fine sander
Does better on large
flat surfaces (I think this is due to the circular edges of sanders with a circular pad digging in ever so slightly into the worksurface...RS 2 E won't do that.). It also has very fine sanding stroke so will not leave any scratch patterns---not as fast even with higher grit, but it is a finisher for sure.
RO 90 DX-->Smaller surface workhorse
For surfaces that don't have a wide surface, this sander is easier to hold and still gets the job done FAST like the RO150---can also get into corners, angle it around things, with a little creativity and soft pads and applicators, you can even do some profiles.
ETS 150/3
Great finisihing sander, use this where RO leaves off for those exquisite finish requirement projects. Easier to control for fine finish (RO150 is not as easy to keep from "getting itself into the work surface" as it is shaped/balanced more for removal efforts in my opinion as opposed to fine finish---it can be done, but its easier to mess up with the RO150.)
Hand scrapers shouldn't be overlooked:
Good Hand Scrapers
Good Gooseneck Hand Scrapers
Saves on paper. It also has the ability to save you time as you don't have to cycle through the grits---it does take some practice and it does take some elbow grease...some would argue, you get a better surface with scrapers too.
For fine sanding, some people don't use machines at all

. Yep good old hand sanding is what I use on my 'last pass' sometimes (and only outside upwind weather permitting).
Other sanders have benefits too, these are just the ones I think you might be looking at right now...and you always have that 30 days to test em' (careful you will probably keep everything you 'test' as you will see how each product will help you! )