Best deli slicer for cheddar cheese

I don't think there's a "best".  I think what you're seeing is "meat" slicers.  By "meat", they mean lunchmeat, not steaks.  The major manufacturers will "grade" their slicers as for what they should be used for.  For $500, I don't think you're going to find anything "new". 
 

Here's a guide by Berkel for their products.  I'm not endorsing a brand, just pointing to a resource. 

http://www.berkelequipment.com/Public/Products/CategoryPDF/BERKEL - Slicers-registration.pdf

Here is the 825A for $800 with free shipping.  According to Berkel, this should handle 2-3 hours of cheese slicing per day as long as it's under 7" diameter, which I'm pretty sure the block you're using would be.  Again, I'm not endorsing a retailer, just providing a resource. 

http://www.atlantafixture.com/ItemD...goryGuid=ae01258a-c8bc-4c00-b1ac-65289cea49da

I have NO affliation with either company; I'm just trying to provide some examples.
 

 

The 12" meat slicers you see in delis and supermarkets cost usually around 3-4 thousand dollars.

Anything smaller than a 12" slicer will "wimp out" when slicing dense, hard items like cheese.

 

For $500.00 you will find nothing new. You are better off with a rebuilt Globe, Berkel, or Hobart. Buy the machine based on amperage (AMPS) as this helps determine power. Some cheeses even on powerful machines are difficult. I drizzle some cold water on mine at times when doing cheese.. Cheese slices better when Ice Cold, and sliced in a cool room. The better the cheese the harder to slice, as good cheddar crumbles when cut. 

 

One caveat.  While amps within a brand or between similar stature brands can be a good indication, beware of off-brands that market just on amps.  Amps refers to how much energy the motor uses, but doesn't necessarily correlate with power OUTPUT.  Also, the big slicers are usually rated in HP as well.
 

 

I have that Berkel 825 slicer......slices deli meats well, but forget about cheese. I only slice about 5lbs of provolone and swiss per week...really puts a strain on it. Belt driven slicers were not meant for cheese.