I use a SS Brewtech Brewbucket classic, and it’s hard to beat for the price. It can’t hold pressure to carbonate, but you can definitely push 1-2 psi of CO2 to transfer the beer out. The flat lid is also nice, and could be retrofitted with a tri clamp bulkhead fitting if you want to modify it. Back when I did 10 gallon batches, I was looking into making my own kegmenter style system with a Sanke that I took the spear out of. For 5 gallons I find this to be easier to work with and clean.
I’m going to try to do some kind of magnetic dry hop release on my next IPA, so I’ll let you know how that goes.