The best invesment you can make is a 180mm or bigger ripsaw. You'll find a lot of uses for it over the years, and it speeds up the work 100 fold.
I personally have a 3HP saw bench, 2 1/2HP ripsaw, 800W jigsaw with ripping blade, a flap-sander disk on my angle grinder and a 1000W Plunge Router. Each is useful for its own purpose..
Bench = Sides and baffles for boxes, nice clean straight cuts every time. Its limited to size.
Ripsaw = Cutting down constructed boxes, or ripping sheets to a size that'll fit the bench. Its not overly accurate, but it'll slice thru 6cm thick hardwood coated with fibreglass without a problem. It'll also cut thru screws like butter
Jigsaw = Tidying up ripped edges, punching sub holes & port holes. Great for curves, crap for straight. You need a phat blade to do anything over 25mm thick.. mine has done up to 10cm thick hardwood but I wouldnt recommend it.
Flap sander = You'll find a million uses for it. Smoothing corners, knocking off "just a little bit" to make it fit, notching, cleaning paint, etc etc etc. Its in accurate and messy, but so damned useful !
Plunge Router = For the the flap sander is too in-accurate, or you want to do something decorative. It'll trim edges nicely, and do fine work perfectly. I use it to round out my sub holes and do edges on smaller boxes.
A. Jigsaw has been used to tidy up the edges that the ripsaw couldnt do. Ripsaws are round, so they wont do a square corner.
B. The edges were ripped using the saw bench. The edges needed to be 100% spot on for the sheet to fit inside the cage, you can't beat a bench for accuracy.
C. Internal cuts are fiddly, and this one needed to be reasonably straight. The sheets are also 50mm thick, so the rip saw was a perfect choice. 60 seconds with a ripsaw, 15 minutes with a jigsaw, do the maths.
D. On the reverse of this baffle I have smoothed out the back of the baffle, so it looks like an areo port. The router was way too small, so some skillfull flap sanding yields the desired result.
E. Again out comes the jigsaw to notch the corners. These are the sorts of jobs a jiggy is perfect for, small and accurate cuts.
F. I like to smooth the front edge of all my sub holes so they fit a bit easier. A bullnose bit in the router is the best match for this type of work.
Obviously, the sub holes were punched using a jigsaw.. thru 50mm thick MDF this took ~25 minutes per hole ! A Sawzall (AKA sabresaw) is better suited due to the thickness of the material. Jigsaw's feel the strain around 25mm thicknesses.