Hi Harold. Your question is really open ended. How deeply do you want to get into this? Is ease of installation important, do you want to be able to program the advance curves and if yes how extensively. What about long term reliability, ease of repair on the road - if you use your car for trips?
Many of us use a EDIS system which is taken from Ford, and others. It was in production for 20 plus years, is dead reliable, millions are in service, and parts are available everywhere. It is completely programmable, using a Mega Jolt on board computer, that also has been around for years - it’s so old it’s become difficult to program as modern computers used to program it have moved past it. (Apparently a new Megajolt is available) The system can be purchased from Trigger Wheel in the UK. Installation is time consuming - there are 5 separate components that must be mounted, plus wiring harnesses and vacuum advance, or throttle position sensor. It is crankshaft triggered so timing is dead accurate, and it has limp home capabilities if the Megajolt fails.
123 Distributors make two levels of programmable distributors. These are more plug and play. The first and oldest uses a dial on the side to select one of a number of pre-programmed advance curves, the second is programmed via Bluetooth from your phone. Most folks are going this way. Long term reliability is not yet proven, as far as I know, and if you have an on the road failure you better have a stock distributor with you. Timing will not be as accurate as crank triggered but that may not be important. I don’t have one of these but have assisted a few guys in setting them up. I don’t like any of the curves on the dial one - they don’t seem particularly performance oriented, and the Bluetooth one doesn’t seem as programmable as the EDIS, but in reality these things may not be that important to 97% of users.