We want the easiest with the best long term wear.

Then just leave them as they are -- they are garage cabinets after all.

A good quality enamel paint, or a clear finish. No need to stain unless you want to change the color.

What are you comfortable working with?

Wood with grease and grime ground into the pores are poor candidates for any type of finish adhering. YOu would need to extensive sanding, and use a stain blocking primer like BIN. As a start.

The soil and hand oil will likely not allow a stain to apply evenly. You can prime them and paint them. Then if they are subject to extreme cold and heat they will craze and crack over time.

You could stain them with an exterior opaque stain. That will eliminate any chipping and crazing.

Exterior stain with mildewcides and fungicides and a warning label should never be used indoors. And it won't penetrate or adhere to grease and grime either.

Luckily, I think only one door has an area that shows soil but I am sure it is on all of them to some degree. I have painted furniture, polyed many an item, so I feel comfortable doing most any project.

This is going to be a project, emptying them out, removing shelves, and doing whatever we decide on. Again, would like the easiest option that meets our needs.

" Luckily, I think only one door has an area that shows soil but I am sure it is on all of them to some degree "

Yep and a few days of prep "may" allow them to take a finish or depending on the type of soiling, the cabinets may never take a finish.

There is a LOT of cleaning with naptha, sanding, and priming in your future. SO much sanding. Before you ever get to a paint. Not every housepaint will hold up as a cabinet paint. You should investigate actual cabinet paints, like Renner, Centurion, Envirolak, Milesi, etc., to spray, and their associated blocking primers.