Well, this is a subjective subject with many opinions.
However, after much searching on filters we replaced our cartridge filter with a cheaper sand filter. However, we substituted glass media in place of sand. The claim is that it filters better than cartridge and much better than sand.
Well, it works better than the old cartridge filter we had, but I have no quanatative measurements to show you to prove it.
Generally, the pecking order for filtration, from worst to best, is sand, cartridge, glass and diatomic earth or Zeolite.
We decided against diatomic earth due to its high toxicity and marginal filtration (if any) over glass media.
We selected the Pentair Triton II for our filter. Get a good diverter valve and make sure you oversize the filter for the job. More is better
We have Sta-Rite pumps and I am told they are a good name. Again, over-sizing slightly is not a bad thing here.
As for heaters, that depends where you live. If you are down south in the sun, then solar is more economical. Otherwise, you need a gas heater, which is more costly to operate, but may be a cheaper initial investment.
In Florida screened enclosures are popular. They keep out a lot of leaves, grass and bugs. More important, they provide some relief from the sun. The downside is the expense.
Lastly, after much research we decided to use plain old chlorine as a disinfectant. Salt systems are appealing, too, but just about everything else under the sun has too many drawbacks and issues. We use 3" tabs in a floating dispenser and shock the pool once every week or so.
The important thing to do is keep the alkalinity stable (around 100). Once the alkalinity goes outside of 80 to 120 that is when people have all the horror stories with their pools. Chlorine levels are not as important as alkalinity, but should not be neglected.
Once alkalinity goes outside the range, the process to restore it takes one or more weeks. Low chlorine can be fixed in hours.
Our pool gets moderate to low use, but we have a 70 lb dog that swims as well. Our water is crystal clear all the time and I only need to vacuum once a week or so and it is just a spot job at that.
Oh, beware of the ads for Ecosmart. I looked at those pretty closely and the company spends HUGE amounts of advertising dollars and dozens of web site domains making wonderful claims. I have read too many complaints and it is probably more snake oil than fact.
The same caution should be given to all of the ads that claim wonderful results and swim in bottled water, etc.
Check with a reputable pool supplier in your area and see what works best. Chlorine, when used correctly, is a great choice. A salt pool would be worth considering, but make sure you understand the good and bad.