What filter do you recommend for my Spa?

If the cost was not an issue, should I go for disposable or washable filter to my spa?Actually the cost seems to be just about the same if I pick a washable filter at the higher end. Should I still go for washable filters?

The two washable filters I consider are:

-Pleatco Advanced+Dual Core Cartridge PRDC25-AFS (it is not in Pleatcos assortment but is sold through Coast Spa). I cant tell if the filter is 25 or 50 Square feet.
This filter is with the new medium+is dual core+Antibacterial (is that really necessary?) costs 750 SEK = 82 dollars
The other washable alternative is:
- Pleatcos (normal) Pleatco Advanced (PRB50-In) costs 500 SEK = 55 dollars in Sweden
It has the new media but is not dual core and not antibacterial (but is probably easier to clean and costs 33% less

I also have an option to buy disposable 1 Micron filter that costs 300 SEK/filter = 33 dollars/each.
It doesn’t say what brand but the seller say that it should be replaced every quarter or every 5-6 months if the spa takes 2 filters at the same time (as my spa do).
This means I need 4 filters a year and the cost is actually lower (33*4=132 dollars per year) than if I go for the Pleatco Advanced+Dual Core Cartridge (82*2=162 dollars per year) or equal to the Pleatco Advanced (55*2=110 dollars per year). Not counting the cost for the washing equipment or the time to wash the filters.

If the disposable filters is better (takes care of particles down to 1-5 micron), and save me time to the same cost - It seems like a easy choice.

What am I missing here?

Additional information:

I have a Viskan Ekerö spa 1715 liters (453 gallons) and bathing about 190 hours year (125 persons), which represents 3.6 hours / week (2.4 persons in the bath per week bathed 1hr 30 minute average). I have 2 filters 33.8 length (cm) 12.7 Diameter (cm) in my spa.
I change the water after about 170 days (3 or 4 times per year) and always use pipe clean at each change of water. The TDS is never over 800 OSU when I switch water. Good quality water from the tap. I use bromine sanitizer and active oxygen (MPS) as shock. Always showers before entering the spa. Measuring values 1-2 times a week (Taylor Kit) and always have clear water without any visible problems.