Most sink specs will tell you the minimum cabinet size. The reason the required cabinet is often larger than the sink is to allow room underneath to attach the sink to the counter. They have clamps that usually add at least another 1" on each side. You'll have to check the specs to see if the 28" dimension is the bowl dimension or outer sink dimension.

The dimensions listed are for the exterior dimensions, not the interior dimensions.

This forum usually recommends that you should use a harness/strap instead of clips. If you are lucky, then in addition to being more solid, it might just give you a little bit of extra space.

Other recommendations that you'll see are to prefer a single bowl over a double-bowl design, to get (almost) square corners to maximize usable space, to look for a drain that is in the back and preferably off-center, to buy a ledge-style sink with accessories if you can afford it, and to adjust the depth of the sink to the height of the chef. For most people, that probably means you should look for a shallower rather than deeper sink.

Other questions to consider are whether you want a farmhouse sink vs. a in-counter sink; what material you prefer; and whether you'd rather have a top-mount or an under-mount. But all of these are very personal decisions. I don't think there is a perfect one-size-fits-all answer.

Finally, you should review the reputation of the manufacturer. Most manufacturers make great sinks. But there are a couple of bad actors out there.

I'd recommend you go to Dino Rachiele's website. He makes wonderful sinks, but they do cost a (justified) premium. If you can afford them, you can't go wrong with that decision. And every so often, there are generous sales, but they never last long and usually are limited to a single design.

But even if you ultimately decide against buying from Dino, he does the community a great service with his website. He has a ton of very educational material on what you should look for in a well-designed sink, and why you want those features.

If you strap your sink in place, you may disregard the manufacturer's required minimum cabinet sizes because you don't need room for your hand and screwdriver to access the clips for tightening. I've done this a hundred times or so.

You can put a 30" sink in a 30" cabinet, no problem. I've put a 33" sink in a 27" cabinet.

If you ever need to change your sink, you'll really be glad you strapped, believe me. One or two easily accessed nuts to loosen instead of 12 nearly impossible ones. Plus you can have the more desirable skinny front top rail because your fabricator doesn't need the room clips require.

Hercules Universal Sink Harness from Braxton Bragg or a Sink Strap or two from Regent Stone Products.