I'd suggest Gnucash, but it is not the simplest thing to learn unless you're an accountant who does double-enty bookkeeping regularly. Have you thought of using a VM for Quicken? I have one program that I can't run natively in Linux, a simulator for remote controlled airplanes and helicopters (RealFlight). It works great in with vmware-player.
Thanks for the tip. Yes, I’ve been using VM to play with different Linux distros. I know I have that option. But since I’ve already got Quicken set up on my Windows computer, I’ll just leave well enough alone for now.