Belt's GOTTA be tight, otherwise the gun will sag (even more, it will tip to the outside if its center of gravity is higher in a "high ride" type of rig), which will be annoying and uncomfortable. If it's made right, proper tightness will still be comfortable to wear.
I've tried several dozen gunbelts, and I prefer a 1.5" width double thickness leather belt.
A 1.75" wide belt can only be worn with jeans, and 1.25" won't provide enough lasting support for a full size sidearm, while a 1.5" belt seems the best compromise of support plus "useability" with all but modern "fashionable" dress pant belt loops (which I don't buy).
There are MANY good gunbelts in this category.
Lou Alessi's are my favorites (they look more like dress belts), but there are many viable choices. OTOH, there are also many inferior or less-than-the-best choices, of which I've had quite a few over the years, hence I'm sticking with what works consistently.
It's also a good idea to have more than one, not only so they last longer, but so that you can coordinate them with different clothes. (I have several of Lou's belts in black and brown for this reason, since the front of the belt does show.) In several years' daily use, I have yet to wear one out, which is more than I can say for half a dozen other well known makers.
As to whether the belt should be cut on a contour, it doesn't really make any difference, since the belt will always assume a contour with regular wear, if it's leather.
The various nylon belts are OK for practice and occasional wear. The Wilderness 1.5" is the least offensive of these, in my experience, but leather is much better, IMNSHO. Most of the folks who use the nylon stuff don't (or haven't yet) practiced CCW all day, every day, for decades.
Best.