When I was a kid, Wentworth was our go-to family lake. For most of my adult life, Merrymeeting has been the place. But I'll admit to a fondness for Chocorua Lake, nestled along route 16 between Ossipee and Conway. It has a quiet, peaceful vibe, with very little development along its shores (due to property owner conservation easements and a motorboat ban), and it looks up in a serene kind of wonder at the rocky summit of its 3,500-ft name partner. Canoes, kayaks, fishermen, and swimmers have long enjoyed the clean and shallow waters of Chocorua (at an average depth of 12 feet, and nowhere deeper than 27 feet, the lake is a virtual birdbath).
As a kid we frequently made stops at Chocorua en route to other destinations, sitting as the lake does at the doorstep of the White Mountain National Forest. There are great trails along the shore, and some cool wooden footbridges. My enduring memory of the lake is the unusual stony bottom, so unlike the sandy or mucky floors of most lakes.
The proximity to Route 16 (previously the Spaulding Turnpike and the White Mountain Highway, it's now the Chocorua Mountain Highway - it'll return to the White Mountain name after Conway) and Chocorua's shallowness have made it a fragile lake, vulnerable to runoff and algae bloom. The state's been working to counter the effects, with an 82% decline in phosphorus since 2000 that the EPA has recognized. (At least, it used to - the EPA website trumpets regulatory slashing more than environmental success stories these days.)
I'm a lake guy, and New Hampshire has lots of wonderful ones. There's no shame in landing third on my list of favorites.