I bought 7 brands recently when I used up the 1000 I bought a while ago and they were no longer made. Of those my choice was from cshardware.com and is part#36.410, plus clips part #36.4175.
Some of the ones on the market look like them in the catalog but the long part of the leg is screwed to the cabinet, not cool. It is weak when tipping up tall cabinets and if your cabinets are close to the ceiling will not allow you to tip them up. What I do is screw on all the bases, or use the hollow bolts in the back to allow for adjustment from the inside, stand the tall cabinets up and using a block and lever lift then, then reach under and insert the legs in the base. The ones with the leg attached to the base will not allow you to do this, nor will they allow you to tip the cabinet up. Regular base cabinets can have the legs popped into the sockets on site and then just flipped up.
The ones I pointed out come with nice strong metal clips and the lower foot pad is like a bearing allowing easier adjustment. Price is slightly more, just a few cents, but worth it in my opinion.