I am a bit of a clothes horse myself. In fact, in our shared bedroom closet, I probably account for 3/4 of the clothes in there. I used to have rather bold choices in my wardrobe, but I have toned it down a bit, preferring classic styles with maybe a touch of flair.
The hardest thing I have found is finding a designer who has consistent sizing. I love Burberry clothes, but I find that I need to try on eight shirts to find one that fits right. I have a fairly small frame, and usually wear small dress shirts and sweaters. With T-shirts, it's either small or medium, depending on the brand. Some brands I can't wear at all; Armani Exchange's smalls are too small, but their mediums are too large for me.
I am also pretty particular about materials. I prefer cotton for dress shirts, T-shirts, and pants, and lambswool or cashmere for sweaters. Some elastane is OK on shirts and pants. I stay away from other synthetic fabrics.
I also never buy clothes unless they are on sale. I will buy expensive clothes, but at at least moderate savings. Nordstrom Rack/Neiman Marcus Last Call/Saks Off Fifth is where I prefer to do my shopping, and in Minneapolis, I spent a ton of money at the Len Druskin clearance store.
Dress shirts: I gravitate to Theory for dress shirts. I also have a fair number of Boss shirts, along with an assortment of other brands. My favorite shirt is an Armani, but it is hard to find them on sale. I tend to wear dress shirts in the summer, and sweaters in the winter.
Pants: Almost all of my pants are Adriano Goldschmied. They are the only pants that I have found that look great and fit well. I have a really hard time finding pants I like.
Jeans: AG as well, with a sprinkling of other brands (Chip and Pepper, Paper Denim and Cloth, Earnest Sewn).
Sweaters: Vince and Theory make really good sweaters. The Men's Store at Bloomingdales makes a pretty nice cashmere sweater, as does Neiman Marcus. I like the Ralph Lauren lambswool sweaters, but I have a hard time finding them in a crewneck. V-necks don't look good on me, and I've steered away from henleys and half-zips. I don't like cotton sweaters in general (they seem to age poorly), but I do have a couple in my wardrobe.
Polos: Most of my polos are Burberry, Theory, or Lacoste. I used to like knit polos, but have shifted to pique polos in the past few years.
T-shirts: My favorite brand is Victorinox, but it is almost impossible to find their shirts in a small. I also like Vince, James Perse, ADAM, and Alternative Apparel (the last two brands work better in a medium for me). Banana Republic used to have good quality T-shirts, but I haven't checked them out in a while, and it seems like they keep moving their clothing operations to more and more remote locations which tracks with a decrease in quality.
Speaking of country of manufacture, I have found that clothes made in the US, Hong Kong, Peru, Singapore, the Philippines, and most of Europe to be of better quality. China is hit-or-miss; a lot of designers are now making their goods in China which usually ends up being OK, but sometimes it's not. India can be OK for cotton clothes, but I'm not sure I would trust other fabrics. Clothes made in Cambodia, Laos, Vietnam, Egypt, etc. seem to be of poorer quality in general.