If you have space I agree more than one pin would be better. We used to have 10 or so then we were forced to scale way back and dropped to one pin and a VPIN. The VPIN has been great and its staying but I am always working on it and it cannot replace a real pin. That being said we are adding some pins back into the house now and will be at 3 + the VPIN.
Also having more than one game allows for different types of games. Some games are crazy fast fun, others are deep long ball times and marathons etc. You really need a mix of kinds in your game selection to allow for longevity.
For us we plan to get to 4 + the VPIN. Spot #4 will most likely be a constant rotation game i.e. every 6 months to a year sell it and get something else. The keepers are MB, JJP-POTC, and we are working to acquire our very first pin back into the house as the wife wants it and that is Silverball Mania. If I had more room and more money I would love to be back at 10 games but that just isn't possible.
So an older SS game and a newer DMD game I think would be a great place to start based on budget. Folks have already listed some great choices so nothing really I can add to that list. Good luck with your search and welcome to the insanity, I mean addiction, I mean torture err... welcome to the hobby!