You can't go wrong with a vintage mixer from the Sunbeam, Dormeyer, or Hamilton Beach. These were well-built models and parts can still be found if you need them.  There are likely to be a number from the 70s and 80s in thrift stores; models from the 50s and 60s may turn up in vintage stores.  3 speeds are usually enough for most mixing.  If you are looking for a specific colour, it may take you some time but you will find 'the' mixer for you!

If possible, try to find something locally so that you can try the mixer before you buy it.  The mixer should run smoothly on all speeds and not have an ozone smell. Beware of mixers which barely run or don't run at all on lower speeds - they probably need an overhaul. Also, if you find a mixer that is missing its detachable cord and it is priced attractively, don't pass on it. Someone here will know what kind of cord you need. I have bought a good number of mixers without a cord that worked perfectly once I found one.  Goid luck with your search!!

The GE M-47s. At least, the pre-avocado ones are stunningly beautiful.

I have used the same ones for decades (on a transformer in Germany) and was very, very happy. They are not the most powerful of the vintage mixers, though - the Sunbeam 'Mixmasters' with 'Turbo-Boost' are enormously more powerful, if ugly as sin.

The early KA handhelds are great, the stuff Whirlpool sells today was ripped to pieces be Ave on his website - for good reason. It's pure trash. Whirlpool re-upped the transmission quality of their stand mixers (while doing nothing for the horrendously bad electronic components in their pro- series) but their handhelds, some of which are now in the 'vintage' age range, are to be avoided like the plague. Pure trash.

The governor controlled 10 speed GE handhelds have power to spare, as did the built-by-a-committee of fashion challenged blind people Westinghouse handhelds of the late '50s.

My mother had a GE mixer that was probably a M-68 or at the least something that looked similar to the M-68 pictured above. I can't remember personally using it for anything very demanding--I was not much of a cook or baker at the time--but my mother had it for about 20 years, and used it regularly. It was certainly a much better mixer than the late 80s replacement--but my mother bought the cheapest choice in the store that day... ($13 IIRC--fitting it was 13 dollars, given what a disaster that 80s mixer was!)

I have been using a Kitchen Aid 5 speed Ultra handmixer

I know I've used a KA hand mixer (5 speed, too, IIRC) made maybe in early 1990s, and I remember being impressed by it. It's been years since I used one...but, based on my memories, if it weren't for bread dough, that mixer would probably be all I'd ever have wanted or needed.