Whether you're buying online or whether you have local sources, for acrylics, there are a lot of choices, and not all of them necessarily made for or marketed to scale modelers.
Two very good brands of water-based acrylics are Andrea and Vallejo. You can find them online and also in bricks-and-mortar stores. Here in the US, many hobby shops will have them, as well as the general hobby store chain, HobbyLobby.
Vallejo has two product lines: Model Color, meant for brushing by hand, and Model Air, which is formulated for airbrush use. I have some Model Color colors and can recommend them. I have not tried the Model Air lines.
Lifecolor is another brand of water-based acrylics, which are pretty good. I have a set of US Army colors from the ETO, 1944-45.
Tamiya makes a line of acrylics which are alcohol (or lacquer) based, and thinned best with Tamiya's proprietary thinner, though some use isopropyl, or lacquer thinner (when airbrushing). Properly thinned, they can be brushed on by hand as nicely as any of the water-based acrylics.
The fantasy wargame area of the hobby features brands like Warhammer's Citadel label. They enjoy a great popularity, too, and you can find them online, in hobby shops, and also in specialty wargaming stores (Warhammer has a chain of stores here in the US).
Beyond those, I suggest also craft store paint brands. Three that come to mind are Americana, Apple Barrel, and Folk Art (here in the US). Those are available at the arts & crafts store chain Michael's, and at HobbyLobby, and online. Their advantages are that they are relatively cheap by volume, they thin well with water or isopropyl, and a bottle goes a long way.
I'm sure other members will have their own recommendations to offer, which are equally good or better. The ones I've mentioned are all paints that find themselves in my Farbkastl. I have enamels and some lacquers, too, but I do use the water-based acrylics a lot, especially for figures and toy soldiers, and for detailing.
You can try MegaHobby, too, www.megahobby.com. I was just at their retail store in Magnolia, NJ, on Saturday, Triple A (AAA) Hobbies. They have plenty of acrylics in stock. Heavy on Vallejo, but they have other brands. They have the new Revell acrylics, too.