You’re not interested in constantly fighting against diseases, pests and weeds? Before buying a new plant, therefore, grill the salesperson! Does it have a recurring problem with diseases or insects? Is it invasive? If so, simply choose something else.
Don’t worry this is going to limit your choices all that much! There are dozens of apple trees, for example, which are resistant to scab. Hundreds of hostas which are not attacked by slugs. A decent handful of beebalms (monardas) that don’t try to strangle their neighbors. Even carrots that are resistant to carrot flies! Why then buy a plant that is subject to serious problems?
Prevention is the best medicine: that’s the motto of the laidback gardener!