Digikey does have the easiest to use filtering tool.
Mouser's not too bad.
I don't like Newark's. Avnet is similar, but they are the only source for some things, like TPIC6x595.
And Arrow for some parts.
Others like dipmicro.com, pololu.com, taydaelectronics.com, phoenixent.com are not bad because they have smaller selection of parts, easier to find stuff. Or use use names that are easier to search on.