There's a lot of options and online opinions for LED Town Car headlamp bulbs, I deferred to someone I know and trust for guidance.
I was told the "9005/HB3: S-V.4 LED Bulbs" are the best direct fit and performance from a fellow Town Car enthusiast I know personally who has tried several brands. Take that for what it's worth as I have yet to convince myself to pull the trigger on them for my 2006 Town Car. They're certainly not as cheap as many other choices you will find.
Disclaimer: The link included is just one of several available sources.