My buddy and his sister own homes north of Tustin Marketplace in Irvine. One owns a town-home and the other, a SFR. Both are in HOA's. The town-home has monthly HOA of almost $200, while the SFR's HOA fee is $50. However, the SFR's HOA doesn't have a swimming pool, club house, kid's play ground, gates, etc.
Given choice, I'd take a SFR in a HOA that does have a swimming pool, and a house with decent sized back-yard that I could expand into, if needed. It's much harder to find space to expand in a condo or town-home, unless if you're doing garage or loft conversions.
Many of the homes built in boom era had wasteful floor plans. It wasn't until very recently that I started seeing better usage of dead space (turn into closet/storage space) and additional loft options on the 2nd floor (building over empty space). I also like the ones that convert the attic into 3rd floor-loft.
I'd also suggest checking the community at night to see the parking situation. If you see plenty of guest/street parking avail, then that's a good selling (or buying) point. This might be irrevelent if the property has 2-3 car garage + full drive way.