Into mid-century stuff. I'm 46 so I've been collecting for 20 years, but I'm also cheap - and good at vintage finds. That said, 10-15 years ago was much better for finding deals than now. It's been 5 years since I have picked up anything for the house.
I like Eames. I have:
- a pair of walnut LCW chairs that I picked up with a designer discount around 2005.
- a 1960s ash CTW that I picked up at a vintage store for $35
- a couple vintage fiberglass armchairs from craigslist - one with a rocker base and one with an H base
- 6 current plastic side chairs with H bases - I think it was $500 for all 6 on craigslist
- at my office I have 6 plastic arm chairs with eiffel bases - $600 for all 6
I'm also a bit into LeCorbusier. I have two LC3 Grande armchairs and a loveseat. They are vintage 1960s and have some small cat scratches in them. I picked the set up around 8 years ago for $425 at a vintage shop. After living with them for this time, I have considered selling them. They aren't as comfortable as I'd like and they have a lot of value. I could probably sell the full set and buy a more comfortable setup that would make me happier. I also have an Italian made knockoff LC4 that after 18 years is starting to show it's wear. That is a super comfortable chair. Love it.
Previous to this I had a nice (and comfortable) set of vintage loveseats that were upholstered white. Awesome before kids. They lasted until about two years after kids. Add in the dog and they got super filthy. They are currently stored in my crawl space to maybe be reupholstered some day. Sitting next to them is a pair of Saarinen Executive chairs that need the same treatment.
Old living room setup, three days after move in which is why there is no art on the walls yet.

No longer have the Barcelona chair or bench, or the Noguchi table (glass is leaning up against the wall here), and the Nelson bench is at my office.
I have a few Chinese knockoffs - which I would recommend avoiding. In 2006-2007 I had an online store selling them. Most of the stuff was not that great and some was utter garbage. The first shipping container I received was from one factory and I was not impressed. I kept the store up and after selling through most of that I ordered another container from another factory. It was mostly better, but still pretty suspect. I didn't feel good about selling much of it - although there were a few standouts that were nice. I chose to shut it down even though I was still making some money. I still have in use a Womb Chair, an Eileen Gray table, a couple Arco lamps, and an Eames side table.
Then I have quite a few vintage teak pieces (tables, credenza, desk) that aren't any particular famous design but do make me happy.