If you're just looking for a finish that's durable against abrasion, water, and mild environmental acids/ contaminates, a good high-solids Alkyd enamel will probably do fine-- you're looking to something that comes in a regular paint can, not an aerosol bomb (the aerosols have a different binder package,and they're overthinned for ease of dispensing).
The durability of the finish in this case is mostly down to how good your surface prep is, and what the drying conditions are. (Not too fast, not too slow; don't over-thin if you're going to spray it; the orange-peel should lay down in about 10 minutes. If the orange peel doesn't lay down, it's skinning too fast for the conditions, or you're coating right to the edge of a sag or run. Lighten up your coats.)
Lay it on in medium coats, and take the right amount of time. Don't crowd it; let the volatiles flash off before you recoat, but don't let it skin over, either. Don't over-coat; excess film thickness promotes chipping. My technique is one very light tack-coat, then two medium coats with about 20-40 minutes of flash-off between coats.
As an example:
We painted my 52 chevy truck with an alkyd deck paint and some cheap brushes something like 30 years ago-- after scuffing the (TIRED!) factory paint with some 220 grit and giving it a good fresh-water wash. That truck has been parked under an oak tree with bad brakes for about 18 years now, waiting its turn in the project queue. The deck paint is still hanging in there; The surface looks like the south end of a incontinent dog, but the film is intact and doing its job of protecting the metal. The catalyzed Centari I shot on some of the bodywork 20 years ago failed in about 2004 and I've been out there every other year patching the film with a rattle-can ever since.
If you're looking for a solvent resistant finish, then you're into one of the epoxy products, or a three-part isocyanate product; and then you're into all sorts of PPE and disposal questions.
