It's really dependent on what type of rig you're thinking of. I'm going to assume that you're not thinking about concealment. If you're wearing the holster on the pants belt, there are many styles to choose from; and with a separate gunbelt... the holster style can vary from a cross draw, straight hang, or canted forward or back and then you can get into western, modern or tactical. Your body type will probably play more a factor than most of us would like to admit, especially as it relates to comfort. Your best bet is to find a good shop that carries a lot of different holster types and styles and do the "try it on" thing. But, for general info, I'll try to share what I've found in the last forty years of wearin' guns for work and play. I've worn four basic types: Cowboy rigs, both traditional and buscadero, uniform types (Sam Browne), and plain clothes or undercover types. The first two use separate belts for pants and holster, the last only a belt holster (or shoulder holster).
A buscadero rig is generally worn below the pant's belt. With the holsters riding below the belt, there's not a lot of interference between the two belts (Buckles can be a different story). But, if you've got a gut or are short waisted, there can be. With the typical cop belt, ala "Sam Browne", you wear the gun belt right on top of the pant's belt, held to the pants belt with "keepers". The pants belt needs the smallest buckle that will work... it's strickly function, there ain't no "show". The original Sam Browne also used a shoulder strap to help hold the weight of the holster. Some state agencies still wear the complete rig, tho' most have now dropped the requirement for the shoulder strap. In the words of an administrator I knew, "... looks a little too "Gestapo" for our tastes." The traditional cowboy rig can also be worn in this fashion. But like the SB, the smaller, flatter the pants belt buckle the more comfortable it will be. The gun is best worn in a holster that keeps the grip above the belt line. Once again, body shape will dictate how comfortable or feasible this type rig will be, if you've got a gut of almost any size, the buckles can be downright aggravating! In this case, suspenders instead of a pants belt is a LOT more comfortable. You can sew buttons for traditional suspenders either inside or outside the waistband. The gunbelt can then be worn in any position that's comfortable. If you're sitting a lot, a crossdraw in front of the hip is good, depending on the crossdraw's angle. SASS rules have mandated that the CD holster be no more than 30º off the vertical... this isn't as comfortable as one at a 45º, especially for longer barrels. A "Duke" rig is very comfortable with short barreled revolvers or autos. My favorite 1911 holster is similar to a Duke, but is made to be worn on a pants belt.
For holsters to be worn on a pants belt, I like to have both the front and back of the holster supported with loops, so the belt slides thru them and can be held in position with one of the belt loops on the pants under the holster. The
Bianchi International models I like best are the "Black Widow", (I have two, one each for a Combat Commander & a mdl 65 S&W), the "Shadow II". These are not necessarily concealment holsters, although with a well-fitted coat they can be. I wore them for both UC and plainclothes assignments. Both Bianchi and Safariland are great products and have a huge variety to choose from.
For my cowboy action rigs I wear either pants with a belt, pants with suspenders or in the case of my buckskins, neither, just the gunbelt.With that leather on leather deal, the belt doesn't go anywhere! I've worn my gunbelt with suspenders that have buttons on the inside of the pants like a quality suit, or outside like my canvas pants. I happen to like button suspenders. I just try to make sure that my gunbelt isn't pressing directly on the button. Clamp type suspenders seem to snap open on me, and sometimes buttons come off, in either case it's a hassle, but while the clamps can be re-snapped right away, they're far more aggravating... with the buttons, either keep a handy maiden & sewing kit around, or check them regularly for frayed stitching!
It's just too bulky and on top of that, I can't access my jean pockets for keys or something else. 
