Hello I’m looking for a little advice. I brewed beer from 91 to 98 and stopped so I am considering myself a newbie again. I have been making cider and mead since then though. I want to get back into brewing. I used an eight gallon canning pot before and want to upgrade to a ten gallon stainless steel pot. My question is this. Is it worth the extra expense to get the pot with the ball valve thermometer and false bottom? Or just a ten gallon pot and a digital thermometer? I will be using the pot as a mash tun for step infusion and deconcoction mashes. I am deciding between the Polarware 42 qt and Blichman boilermaker 10 gal. I would appreciate hearing anyones advice or suggestions. Thanks.
If the kettle is stainless steel clad over aluminum at the bottom, make the seller prove to you that its quality and not junk. Test it with baking soda and boiling water… if the water has a bitter taste afterward then its leaching aluminum and its not worth the money they’re asking. You can take that to the bank, or save yourself some bank. 
Bigger is better. I went with a 10 gallon pot and I’m already wishing I got something a little bigger. Give yourself room to expand down the line.
If you’re going to be using it as your mash tun then the thermometer and ball valve would seem to be good ideas. If just using for the boil kettle you don’t really need either however I do enjoy having the ball valve on mine so I don’t have to siphon.
I got 10 gal MegaPot kettle with ball valve.
If you are going to use it as a kettle ball valve is a must and thermometer is nice to have.
If you are going to use it as a mash tun then you also need thermometer and false bottom.
If you decided that you are only going to brew 5 gal batches both pots will work.
if you are going to brew 10 gal batched you need 15 gal pot.
My ten gallon Megapot has been great for me. No valve, no thermo
Do you still have that 8-gallon canning pot? Is it still in good shape? If so, you could use a picnic cooler as a mash tun. That will work fine for stepped infusions using boiling water. You can also use the 8-gallon pot for decoctions by pulling them from the mash tun, heating to rest and boil, then returning to the main mash. Then, I’d suggest you go with at least a 10-gallon pot for your boil kettle and, as others have said, you’ll probably want a 15-gallon boil kettle if you’re going to do any 10-gallon batches. Either the 8-gallon canner or a new pot could do double duty as your hot liquor tank.
My boil kettle is a converted Sanke keg (15.5 gallons) with a valve and thermometer. I like not having to siphon, and the thermometer is helpful for knowing when the wort is first approaching the boil and for watching temperature while cooling the wort with my immersion chiller. Those Boilermaker kettles are very nice if you can afford them, and I think one would be great as a boil kettle. However, unless you’re planning to do direct-fired heating of your main mash tun, I think a cooler is every bit as good and a lot less expensive. The money you could save on the mash tun would go a long way toward setting up good temperature-controlled fermentation.
Go bigger and SS if you can afford it. That being said my Al 80qt is perfect for my needs and I usually crank out 12 gallons. Heats all the mash-water at one-time too.
If you want- get all those extra features. They cost extra but upgrading the Cadillac usually does. You won’t regret it. DIY isn’t always the route to happiness…