One may argue that townhouse will appreciate less than SFH. Yes, in the short term, SFH may appreciate bigger than a condo or townhouse. But over the long term, when your overal median price doubles in your area, it floats every type of property. Regardless townhouse, condo or single family homes, they all appreciate at more or less the same percentage.

However, it's a huge different when you have to consider holding a property. For example, in my area, a townhouse can generate $1800-2000/month rent. But a SFH can generate only 2500-2600/month. But I can't afford to hold a single family home, they are too expensive. There is no way to make a big Single family home even cash flow. So, buying a luxury single family to invest is a bad business. Don't confuse your personal love for single family home as a consumer with your goal as investor. If you get confused, you make a mistake.

When compared to $600K SFH and $300-400K townhouse, no question about it, choose townhouses.