One of the best threads for hand quilting is from the Big Box store in a bin for .99 a spool. Made by A&E and comes in several colors.
Otherwise I use whatever I have. If it really doesn't work then I toss it. I have used older threads that work well. I like the Coats and Clark older thread and buy it anywhere it is still available. It is cotton wrapped poly and machine and hand works well. I've bought boxes of older threads from Good will that work fine on my charity quilts. Test it and if it breaks easily, then there is a problem but if strong then will work.
Also,. when you buy thread, some of the more expensive larger spools may be the best value. Check the quantity on the spool and calculate like the grocery store calculates items per once or serving