Spray painting furniture is preferred if there are many detailed angles and textures and hard to reach corners. Rollers and brushes will quickly fill such textures and leave marks.

Otherwise, for large flat surfaces like shelf/table tops or doors, a roller or brush is fine too.

Further, it's easier to get a gloss finish with a thin layer of spray paint, since a roll on requires a thick application.

This is my amateur experience. A professional may get great results with a different tradeoff between the two techniques. Sometimes amateurs need to do it differently to get acceptable results, limited by skill and tools.

As for oil based (a.k.a. enamel) vs water based (a.k.a. acrylic), here is a good overview:

The surface prep for acrylic paints is a bit more involved in terms of applying the right primer. That's why they are a great candidate for the automotive application where prepping and priming is already quite involved, and requires diligence and skill.

Oil spray paint will attach easily without any more prep than sanding and cleaning.

As for water resistance: there are great water based paints and finishes available for surfaces exposed to water, but your options from the manufacturer may be more limited than the vast array of tints and colours that are oil based and water proof. As for pre-canned acrylic spray paint, the options are even more restricted.

Fumes and drytime are usually not an issue when it comes to ikea home furniture refinishing, so for these reasons I'd go with the benefits of oil spray paint.

Ref: https://acrylgiessen.com/en/enamel-vs-acrylic/

To determine wether the base of a spray can paint is oil or acrylic, have a look at the specifications, under "Base Material":

You can also search for "Base Material Acrylic"

Generally there is a line of products under a brand name, e.g. "Max Flex", that is of a specific base. Here they tout the higher flexibility of acrylic paint over the harder enamel paint.

Ref: https://www.homedepot.com/p/GLIDDEN-MAX-FLEX-12-oz-Matte-Black-Interior-Exterior-All-Surface-Spray-Paint-and-Primer-GMF1011-54/319420374

Spray cans are usually the more expensive alternative, but they are easy to use without having to clean spray equipment.