I would say Newmarket (80,000) or Aurora (53,000).

I realize these may not qualify as small towns, but good in-betweens for 30 minutes to Barrie, 30 minutes to Toronto.

Consequently they're both commuter towns, extremely high standard of living IMO, but property is expensive; especially Aurora.

Both areas are somewhat hoity-toity (every 3rd or 4th car is $75,000+) But rates for renting are very reasonable, and there's opportunity to work for large companies and very small boutique business too. The downtown core of both towns haven't been impacted badly by big box stores either, it seems.

The main advantage to me is the incredibly ease of access to Toronto via the GO Train, and all the major ski resorts and Wasaga beach (for the summer) is just 30 minutes - 1 hour away too.