There are a LOT of variables here. The 6x16 tandem you show the link to seems terribly high $ but with brakes and the way it is shown you probably will not do a whole lot better than that. I see several around that price. The SLE brand in your second link looks better EXCEPT that frame doesn't look so sturdy. The width is improved. The beavertail definitely helps.
There really are a LOT of key questions about your needs:
1) How often will you use it per year? 2) Do you really need brakes ? 3) Is your towing vehicle overqualified (exceeding 6000 lbs) or light in the loafers like a Ford Ranger or Chevy Colorado? 4) Will your towing be in your local area or mountains with steep roads, etc.?
From the data you supply the Polaris and the B2920 will not challenge a trailer with those specs.
First thing I would do is find a wider one. 6ft will not accommodate even a BX2200 with a belly mower.
Second, do you really need tandem axles? You can buy a single axle 14ft that will readily haul what you list for around $1500 less. Maybe $2500 or so.
For example my Stagecoach brand has an upgrade stronger axle, stronger than std tires, 78" wide bed, small amount of beavertail which helps a huge amount when loading AND makes the tailgate much shorter and easier to lift without springs. It would very easily handle your loads that we know about. It cost me a hair over $2000 via dealer in Bossier City LA 4 years ago. See
Utility Trailers For Sale New & Used | Topps Trailer Sales in LA dealer website in Bossier City. I do not know where all Stagecoach has dealers but they are made in TX, are VERY well made and durable. The mfr is super receptive to doing mods and custom stuff to suit you at not exorbitant prices.
The top rim frame is heavy 2"+ size pipe, a lot stronger than thin angle iron. I've owned both.
I added mesh sides, extra post holder slots, a spare tire holder, etc.