Narzog wrote: the cheap factory whistles, which people usually say to go to your local store and try them all and pick the best one.
Yes faced with these options
1) go to a shop, try them all, pick the best one
2) go to a shop, try them all, pick a less-than-best one
3) go to a shop, don't try any of them, and grab one at random
4) buy one blind online
I will take my chances with #1.
Though I had a student who did #3 and got a great whistle (in contrast to a hundred other people I know who did that and got a mediocre whistle).
When I started playing everyone played a Generation D, the professionals and the beginners alike.
You tried every one you could get your hands on and sooner or later ended up with a very good one, a convergence of you learning more about what distinguishes a good whistle and you having played an ever-larger sampling of them.
Or your teacher picked out a good one for you from the get-go.
Which reminds me of the American visiting a big festival in Ireland who got interesting in learning Irish flute, he was at a booth trying (as best he could) all the flutes on the table. Matt Molloy walked up, asked "looking to buy a flute?"
"Yes my first one."
Molloy tried them all, handed one to the American, and said "buy this one" which the American did do.
Which I think is the ideal way for a beginner to get a good instrument.
Now about the whistle makes mentioned above, here are my experiences with their tuning:
Tilbury: I haven't played one.
Killarney: I have two Ds.
The 2014 has perfect octaves but odd tuning issues with the tube, which I switched out for a Generation tube, giving me a perfectly in-tune whistle.
The 2018 has good tuning regarding the tube but a flatter 2nd octave than I would like.
Burke: I've had Burkes in several sizes from High D to Low D and as best I recall they all had a certain tuning quirk, most pronounced in the Low D.
Goldie: I have Goldies in three sizes and the tuning is just how I like it.
MK: I owned a half-dozen different MK Low Ds and all had a certain tuning quirk.
Chieftain: This covers a lot of ground! A long history and numerous different iterations. All I will say is that I've tried a large number over the years and the only ones I bought were a couple of the early ones made under license of Bernard Overton.
Shearwater: I haven't tried one.
Susato: I used to own Susatos in a large number of sizes from Low C up to high D. The three or four Low Ds, a Mezzo A, and a high D had great tuning. But the tuning of the other sizes was all over the map, each whistle having a uniquely out-of-tune scale. Happily the Susato plastic is easy to carve, and with a combination of chopping, carving, and taping I was able to get all of them in tune.