Generally, the #6 switch or “Turnout” would represent a “High speed switch” (In real life a high speed switch would have a much longer frog angle…but that’s about the largest you will find in a ready made LS switch these days.
The High speed switch would be used on the main line, and smaller “Frog angle” switches like the Aristo Wide Radius, whould be used on secondary trackage in a yard for example.
In any case, all equipment looks, and functions better on the widest frog angle switches, along with the widest curve you can use. It makes very little sense to buy #6 switches when your widest curves are less than 5 foot radius.
When planning your railroad, think about the future.
What do you think you might enjoy running on it in a few years’ time…if it’s your hope to run BIG Diesel power or articulated steam locos, along with full length passenger equipment…then go to the widest curves you can fit in your outdoor location, along with the #6 switches…
The Wide Radius switches are fine for most situations, where you are running smaller locos, like an Aristo Alco RS3, or a USTrains GP7…or most of the smaller steam locos like the B’mann Annies, and the larger Connie (2-8-0).
My suggestion is to NOT use anything smaller than a 5 foot radius curve; #6 switches on the main line, and Wide Radius switches in the yard area.
Good luck.....and yes, the cost of switches is also a factor, but DON'T use the very much less expensive 2 foot radius switches....they are only good for VERY small 2 axle locomotives and cars.........plan well, and ask lots of questions, before purchasing anything.