I have a 1970s Kenwood Chef which I just love. It belonged to my Grandmother before me. It still has the cloth cover with the embroidered strawberries on it that she had. It seems bulletproof, and strong despite having only a 300 watt motor. Its only problem is it is very noisy, normal for ones of that era. I use it on a folded tea-towel to minimize noise and vibration on the benchtop.
Having said that, about 2 or 3 years ago I bought a little Braun Multimix for when I wanted something quick and easy instead of heaving the big Kenwood out. It was on clearance at the time, I think about $30 when they had been $120?
I think it is great, in fact since I got it, I haven't used the Kenwood at all...
At work (I was a cook for nearly 30 years, in my last 15 years I made cakes most work days) I used a slightly newer Kenwood Chef, it was very robust again and made great cakes. It got tired after being thrashed for over a decade, we replaced it with a similar looking Breville, which proved unreliable - it would strip a gear when making my carrot cake mixture. It did that several times. The Kenwood made hundreds without issue. We briefly used a Kitchen Aid and I quite liked it, but it was very noisy and didn't offer anything the Kenwood didn't offer.
My big advice is that the slowest speed is probably more important than the highest speed. You want a machine with a well-controlled (governed) very slow speed, capable of combining dry ingredients without throwing them around your kitchen. Many cheap machines don't go slow enough for this task, they fling your ingredients on the walls and on you, so you have to combine by hand with a spoon before using the mixer. The old Kenwoods like my Nan's have an internal adjustment for the governor, you can adjust it to turn really s-l-o-w in little bursts, it's great for that initial combining of ingredients. Try to get a test run before you buy. The little Braun goes nice and slow on its lowest setting.