Adding a couple of,automated control valves is pretty cheap compared to adding dual equipment. In the end, it depends on what type of controller you have. If,you,have an automated controller that will manage pool and spa you likely can share equipment between both. Without that you would have to manually,switch valves each day to run both- a pita.

I agree with Ross.

Start with a single equipment system, shared, and install some automation now or go manual but plumb now for the option of automation in the future.

Equipment recommendations can be quite subjective, but I'll offer my experience.

Heater: When my pool/spa was built it had a Pentair Minimax propane heater installed, 400k. For a spa, you want the water heated quickly, I'd recommend a 400k. Simplistically, (and I emphasize the "simplistic" part of that, lol) a 400k heater will use twice the propane that a 200k heater will use when it is firing, but it'll fire for half the time. So it will heat up your spa faster while using the same amount of fuel. Me? When I want to jump in the spa, I want to get in NOW, not in 45 minutes, or an hour. So the 400K was worth it to me.

I had troubles on and off with the Pentair Minimax. When the Pantair finally bit the bullet, I replaced it with a Raypack 400k heater. The Raypack has been a treat. Zero issues, very easy to DIY maintain.

Pump: Get a variable speed pump. I started with a Pentair Whisper 1.5hp single speed pump years ago. It circulated water well, and by itself it takes care of the four jets in my spa when the spa was in use. When it was running I think it drew 2000-2400W.

Maybe three years ago I replaced that with a Pentiar Variable Speed pump. The VS pump paid for itself in the first year. Most of the time it's on a low-flow setting, the speed I have set draws about 200W of current. It's programmable, and scheduled to run on low for most of the day and kick up to high speed for 1-2 hours a day for cleaning, it also kicks up to high speed when the spa is used.

The first year I had it I ran current draw numbers, on a daily basis it used about 1/8th the amount of electricity that the old single speed used. It paid for itself in electrical savings in the first year.

Filter? I started with a Pentair cartridge cleaner. "Clean and Clear" was the model I think. Maybe a C&C 240? Worked fine. When I replaced a few years ago I stayed with Pentair, but went with a hybrid of sorts, the Pentair Quad DE100. It's a cartridge design, but the cartridges get coated with a layer of diatomaceous earth. The DE100 is oversized for my 20' x 40' pool, but I have not had to clean the thing during the swim season. Prep it in spring when I open, let it run all year, then clean it in the fall when I close up. I like it as well.

There are certainly other options. But as a homeowner, that's the advice I have to offer.

Right on point Mongo!