We had a laundry list of things we must have versus things we could live without versus things we couldn't stand.
First, we rented villas in different areas - we knew immediately we didn't want a condo so that narrowed things down quickly
Re condo versus house: Aruba is different from where we're from as you pay a premium for condo living here because a lot of them are on the beach... houses are cheaper when you look at the price per square foot.
We wanted to live away from the tourist areas and wanted our own pool so that threw condos out immediately. We did consider a sort-of compromise at Tierra Del Sol but didn't really see anything that suited us so we ended up buying inland. And we haven't regretted it.
If you do opt for a house, be aware that some chunk of your time here and away will either be spent repairing things (the salt air is brutal on homes) or coordinating repairs. Constantly.
We knew what we wanted in a vacation home both of us having spent a lot of time in Florida growing up. For us, it was all about the weather and we'd just roll with whatever challenges came our way. It was important for us to start laying down roots as soon as possible.
We knew the minute we landed on our first trip in 2008 that Aruba was the right place for us. We came from minus 25C to 33C in five hours (it was rainy and cold in Florida that day).
But, if you're not "sure", I agree with the above posts: rent a few places in your target areas before you pull the trigger. And get a good real estate agent who understands the ins and outs of purchasing in Aruba and the notary process.
Good luck! Keep us posted!