Year Built is a factor however you need to look at what you are getting vs. what you are not getting. Aliso Viejo has newer homes and is closer to the beach than Mission Viejo but you will get more sq. ft. and a larger lot size in Mission Viejo vs. Aliso Viejo. You'll pay a premium to buy in Baker Ranch since it's a NEW development and I believe the lots are smaller as well. Keep in mind, when buying in a New Development, the earlier phases are better for appreciation. When looking in Laguna Niguel, the majority of the homes in your price range were mostly built in the 80's - range from late 70s to early 90s. There's not a huge difference but newer homes will / should be priced higher than older homes depending on upgrades and condition of the homes of course.
Here's a great article from bankrate.com:
Here's a quote from that article: "The cost of repairs, maintenance, replacements and upgrades tends to make older homes less desirable, and thus more affordable than newer residences, even though the savings at the time of purchase is often offset over time."
If you are looking to hire an agent and haven't already done so, I would love the opportunity to talk to you about your situation.
If you are looking to sell the home yourself, I would be happy to provide you with a host of free marketing material specifically designed for internet advertising on Facebook, etc. I make this available to any homeowner that wants to try to sell their own home without an agent. Hope to hear from you.