Yes, all three are from reputable brands with good reviews and similar manufacturer warranties. From what I usually see the pricing is usually Samsung 860 evo > Crucial MX500 > WD blue (might vary depending on where you live and what retailer you buy from), and performance is pretty similar. Just get what is cheapest and it should be fine.
It should be fine. It has a small emulated SLC buffer but can still write at ~400MB/s once its exhausted that.
The 860Evo & MX500 uses a variable SLC buffer size based on the free space the drive has left.
I know the 860 min/max size is 6gb/42GB . I'm not sure on the MX500.