So I am upgrading to a 15 gal kettle, any reason to spend the extra $ to go with anvil, spike etc over the Bayou classic?
That’s simply personal preference. Like arguing Ford vs Chevy. It’s up to the consumer to discern the difference and wether that different represents value enough to warrant the extra cash. The old adage comes to mind: buy once cry once. But if the cash isn’t there get what you can to produce beer. No one will every take a drink of your beer and say, “Dude. That beer is awesome. Did you brew it on a XYZ kettle?”
(btw: Ford)
Spike or Bayou is more like Mercedes or Ford.
In Germany Mercedes and BMW are Chevy and Ford. 
I haven’t used any of the three but if the specs are reasonably close on them, I usually buy the middle. Not the cheapest, not the most expensive.
Paul
Scrap yard 15 gal pony keg. Cut out the top to match your lid. Nice oak plug for bung hole. Be sure quarter turn tap hole is near bottom for gravity transfer already there. Weld on a tripod of EMT legs to get desired burner height. Some states require kegs to be drilled prior to discard. Just weld up the hole. Ten bucks and a fun project.
Jim
The key characteristic of any pot is a thick bottom to dissipate heat and prevent scorching. Very important if you plan to boil 10 gallons. I use a 20 gallon Spike to boil my 10 gal batches since I start with about 13 gallons. Very happy with the quality of Spike and they are less expensive than the Bayou Brew Kettle. And for the record, Ford over Chevy.
+1 I’d say the bottom construction becomes a consideration for an induction cooktop as well. I boil 7-8 gal in a 10 gal BK.