Usually I purchase what I know, what has some familiarity. Had a Marantz HT receiver for 10 years. When that stopped working, got another Marantz to replace it, but went a couple models higher.
Same generally goes for my 2ch, got something cheap that looked cool, had good reviews. If I like it, might try to upgrade to a higher model or line. My first TT as a adult was a Pro-Ject, so after 6mo, upgraded to a far better Pro-Ject, have been very happy with it.
Usually that method gets me what I'm looking for with low risk. Since I generally want the top of any line, usually get stuff used.