I occasionally buy all of these, but only the Granges in most years as it tends to be the more consistently good QPR. Guion Cuvee Prestige and Deux Monts can occasionally hit some higher notes, so in quality years like 2014, I often often them both. Joguet Petites Roches has more off-moments. The couple dollars difference between the Guion Cuvee Prestige and the base domaine makes the base domaine a pass. I think these are all a couple dollars more now, and Deux Monts now around $25+. In quality years, the Baudry is an easy case buy for those that enjoy nice wines with most dinners during the week.
I like all the ones on the list to some extent, though the Guion domaine and prestige I’m kind of so so on. The Joguet, at least when I’ve tried it, has been very old school, with some notable green flavors; I like it, but would avoid leaner vintages.
Other good-to-great cheapies include Coulaine Chinon Bonaventure ($18), Bel Air Bourgueil ($16), Domaine de la Butte Bourgueil Le Pied de la Butte ($22), Alliet Chinon ($20), and Y. Amirault La Coudraye (about $25). There are also some nicely drinkable Saumur and Saumur-Champigny wines in the $25 range.
As the question is posed I would say the Guion Domaine. As Robert mentions, it’s worth buying the Prestige since the price difference is so little, but I can enjoy the Domaine, and in some years there doesn’t seem to be much difference. For what it’s worth I think that the Guion wines improve quite a bit over time, and that the Granges is much better for drinking young. Bonneliere’s Rive Gauche is another contender in this price range, and Chateau D’Epire’s Anjou Clos de la Cerisaie. Most of these entry level Loire CFs benefit from riper vintages, but those have become the norm in recent years.
Although I can’t say I drink a lot of Loire cab franc (I am moderately sensitive to pyrazines and prefer it in riper years when they’re in the background), Cris’s recommendation here is one I’ve enjoyed in multiple vintages.
I’ll also second the Tuffe—really nice wine for the price. Another good one in the same price range is Fosse-Seche Eolithe. Both can evolve nicely for 10-15 years in decent vintages. Filliatreau’s Le Grande Vignole is good too, and under $20; I lean towards drinking it on the younger side though.