Definitely go with the bigger filter whether it's cart or sand--I'm biased toward sand, because that's what I have.
What you want is a filter that has a greater capacity for flow than the pump can put out. Otherwise you will get reduced performance and a damaged filter. 1hp, even up-rated should be FINE for your pool, if not too big.
Since I'm a sand filter guy, I'd got with the T180, or make the jump to the T210--it will easily handle your pump's capacity. I have a 1hp 2spd Hayward Superpump--full-rated, and the T210 is fine with it on full speed. On low speed, it filters even better.
Plus there's the under-$10 upgrade to sand filters---a 10 lb box of DE powder (used in DE filters). 1/3 to 1 cup of DE into the sand makes it REALLY polish the water. And that 10# box lasts and lasts. I've used less than 5# since last August.
All you do is add 1/3 cup of DE into the skimmer, wait 20 minutes and see if your pressure rises. Repeat until pressure goes up 1 lb. Usually, 1/3 to 1 full cup will be all you need--and if you overdo it, you just backwash!
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