I use an old Olympus WS-700M, though I did buy a different voice recorder recently and haven't used it much yet. The WS-700M works fine for its designed purpose. You can start recording basically instantly and the replaceable and rechargeable battery lasts forever. I think almost any voice recorder nowadays would work fine. You can use your phone if that works for you. It's a mature field. I just record things and delete them in a day or two. The WS-700M does also make a good MP3 player if you want something disconnected from the Internet.

thanks