I mostly just cooked at home (your cheapest option by far) or had bocas at the bars so some of my restaurant recommendations are from the people that live here; the ones in the know. They do tell me that it's an unfortunately short list of good places to eat where you get what you pay for.
In addition to the places listed, here, keep an eye out for barely noticeable street-side places serving local fare that pop up from time to time. And don't forget to check out Where to Grab a Drink (and a Bite) in Monteverde.
In the SuperMega Shopping Center
There are a few places to eat in the shopping center near the TransMonteverde bus office, including a few sodas (local eateries) like Soda Lety. On first look, it's not the most attractive setting, but there's a nice view from upstairs. The Green Restaurant is the best with a more upscale menu (be careful not to end up in the super pricey place next door), and there's a good panini shop downstairs. Sabor Tico is okay Costa Rican food and actually has 3 locations around town. Prices are fair and they have local cuisine like casado and fried rice.
Tired of gallo pinto? If you're looking for something a little more western, this quaint coffee shop just off the south eastern tip of the triangle is your place. Paninis, crepes, desserts, smoothies and more - delish. Around C3,000 for a specialty coffee and C2,000 for a smoothie.
A hole-in-the-wall Italian restaurant. One of the best in town. It's on the road to the Monteverde Cloud Forest, just across from the Bat Jungle.
Cuchara de Abuelo
Tucked in the back of the CASEM artists co-op building, there's a small restaurant with varying speeds of service. They have fresh juices and typical plates. And you get the added bonus of seeing the local artists' offerings on your way through.
Tree House Restaurant
The Tree House Restaurant & Café is one of the more iconic places in town (downtown in the triangle). You can't miss it with the giant 50 year old tree growing in the middle of the building and stretching to the outside. It looks really cool at night with lots of colored lights. It's trendy and pricey with bad food but it has some cool factor. Not a budget pick, or a good pick at all, but apparently it's very popular.
I'm only listing this here because if you want to go to the place that the guidebooks tell you need to go, it's here. They try to appeal to a younger demographic with their "F'n Good Tacos" sign and prices have become inflated. However, there are often sloths spotted in the trees behind the restaurant along Calle Paraiso so it's a good landmark!
The Open Kitchen / Tap House
This place is more upscale so expect the prices to reflect that, but it's not overly expensive at all. They also have good vegetarian options. If you want a quick bite, you can get a nice bowl of edamame for only C1,500. Eat upstairs in the restaurant or downstairs in the bar. Shout out to Candy and Emel - super friendly and helpful staff in the bar!
UPDATE March 2021: Still closed due to COVID.
Right near the Monteverde Butterfly Gardens, is this preserve meet hotel meet restaurant, all with an amazing sunset view. The beers cost a bit more than other places in town, and you have to be careful not to rack up a hefty bill eating the locally sourced food "where the mountains meet the sky", but it's a really nice place to enjoy a pizza and watch the sunset. Sometimes they have live music, too. I have to say that of the pizzas I've had there, the regular veggie one was the tastiest of the lot and also by far the least expensive.
Celajes Lounge at Hotel Belmar
The Hotel Belmar is a fancy resort and has a lounge with their own microbrewery and an incredible view all the way to the Pacific Ocean and signature garden to glass cocktails. As you can imagine, it's pretty expensive BUT they have a somewhat non-impressive happy hour that they call Tico Time (1/2 price house wine and bottled beer, free bocas with a regular drink).
Go there for some snacks or a beer and to watch the sunset. It's amazing. It's on the road to the cloud forest and up the hill to the left at the trail to Cerro Amigos (the hike up to the radio towers).
UPDATE March 2021: They have now opened a tap room down by the pond where you can sample their craft beers.
Bar Amigos big disco in the heart of town that also serves a full menu. I'm not sure if I'd go there just to eat, but if you want to have a few drinks, maybe dance, listen to music, hang out with locals and other travelers, this is the place. There's live music on Fridays. It's down a small offshoot in the triangle.
The local's bar in the back is one of my favorites, but the little restaurant in front is great for some inexpensive local fare such as casados for 3,000 colones.
I love this small simple local's place with a view to die for. They have a full bar and fantastic, reasonably priced food including the best patacones I've had so far. They have free bocas until 9pm and you might even see Capuchin monkeys while you're there! It's on the road leaving town to the south.
UPDATE March 2021: The place is now called Marisquería y Restaurante Manolo's. It looks pretty much the same but I have not eaten there yet.