A few of my (close to hand) paints:

I used to use Humbrol enamels exclusively but in the eighties (longer ago than I care to remember) I started using acrylics for D&D type figures (mostly the Games Workshop/Citadel and Miniature Paints ranges).
Over the years other ranges have crept in (and out) of my paint collection.
Enamel-wise I still (90%+) use Humbrol but have also started to use the Revell and Colourcoats (originally owned by White Ensign Models; now owned by Sovereign Hobbies) ranges.
Acrylics I commonly use are Vallejo, Ammo by Mig, and AK Interactive. I also use a few of the Games Workshop washes (mainly Agrax Earthshade and Nuln Oil), as well as their Teclis Blue (for cockpit canopies etc.) and have recently used their Valhallan Blizzard (for those snowy bases). I've also tried Tamiya acrylics but found that they didn't (at least for me) brush paint very well. Another problem I (and it does seem to be just me!) have a problem with acrylic matt varnish - I've never found one that dries completely matt. Or it dries white. I've also got one or two of the Humbrol acrylics which are fine but I find that they're not as hard-wearing as their enamel counterparts.
In regards to washes I have read/heard that it's advisable to use an acrylic wash over an enamel paint and an enamel wash over an acrylic paint as this will prevent the paint lifting.
And a few of my brushes:

One more thing: If you do use both enamel and acrylics I recommend that you use different brushes for each. Now the experts will say that you should use the most expensive brushes that you can afford and use sable for x and synthetic for y, but I use fairly cheap (£2-£3 each) synthetic brushes by Creative Models. I commonly use 000, 0, and 2 brush sizes. I try to have two on hand (one for the enamels; one for the acrylics) and a spare for when of the others loses it's point. I use a bit of Tamiya masking tape around the end of the brush handle and the little plastic cover to identify my acrylic brushes. I've also seen it recommended that you use another set of brushes for metallic paints but I've never found the need to go that far. Although I do have another brush that I only use for varnish.
Once a brush loses it's point I relegate it groundwork painting, applying pva glue etc.
<edit> One more thing (I feel like Columbo) I find that a larger brush (say a 000) that holds it's point is better (for me at least) than a 5-0 or 10-0 as it holds more paint and I'm not constantly back and fro to the paint pot / palette.