Tom,
It depends on how you are physically built... Some folks can wear paddle holsters with no problem, while others have trouble. I have and use both. I have found the Galco paddles work very well for me, and the paddle on the Blackhawk Serpa rigs work so well that you can have trouble actually getting them off. (I loaned one to a MNPD employee one time and when he tried to get it off he actually had to go to the restroom and undo his pants to reach in and get the paddle hooks to "let go.") Depending upon how much weight one carries, or how sharp their hip bones are, paddle rigs can be downright uncomfortable...
Everything is a tradeoff... It is nice to be able to come home and "download" the hardware just by slipping the paddle holster off of the waistline of my pants. The down side to that is, depending upon which type shirt I am wearing, paddle holsters sometimes can cause the shirt to "bunch up" either forward or aft of the holster. Not a big deal, but just a little bother that I don't like.
With the belt rig, I can be assured that unless I suffer a belt failure or a true "holster ripping" confrontation, the holster isn't going anywhere. Nice and secure. The downside is that I don't have the ability to "download" the rig quickly if I have to for some reason. I have long arms and have to carry at the 4 o'clock position in order to be able to draw smoothly. I can not move the holster from a 4 o'clock carry position (with belt buckle being 12 o'clock) to a 3 o'clock or more forward position should I wish to do so when getting behind the wheel. The firearm is trapped between my back and the driver seat. This makes it harder to draw the weapon while seated should you have to do so. I can easily move the weapon from 4 o'clock to 3 o'clock with a paddle rig.
I use a Blackhawk Serpa paddle holster (the holster comes with both paddle and a belt slot back plates) about 75% of the time. It fits my Glock 17, 22, and 31 since they are all three the same external dimensions. No comfort issues at all. I have found the same to be try with the Galco Kydex paddle rigs, and even the "ugly" Fobus paddle rigs.
Other times I am carrying my 1911 in a Galco Concealment Paddle rig, nice leather, but with a plastic paddle with a curve that works well for me. For this set up, I also have the matching Galco two magazine pouch with the paddle. It rides comfortably on my left side. Two paddles, one for holster and one for magazines - no issues for me.
I do not limit myself to only paddle rigs though... Bianchi Cyclone #111 (crossdraw or strongside dual purpose) for a 4" S&W .44 Magnum, a Galco Concealment Belt rig for a Glock 21, etc. I have several belt rigs, a couple of which I have made myself. They are very, very comfortable as well.
This is a strong-side pancake style holster for my S&W model 10-6 (1971) that I stitched up on January 30th, while the snow was keeping us house bound up here on top of the hill:
This is a 4.75" Colt Single Action Army crossdraw rig I stitched up back when we had an earlier snow in January... I even made matching ammo loops to slide onto the belt as well. (The snow keeps me in, so I have to do something creative!):
Both of these rigs are nice and comfortable... Made with the loops just the way I wanted them, and made to ride on the belt just where I wanted them to ride.
Once I make rigs like these, I use a combination sealer/dye that keeps the water out and helps to maintain stiffness and the deep boning (molding to the firearm) of the rig. Why make these rigs? Well, I couldn't find exactly what I wanted... I looked all over the internet and in magazines... Then combined the features I liked from the different rigs I saw. I have maybe 16 total hours of work time in the two holsters you see here, and maybe $35.00 in materials. But it was something I was doing for myself... I suffered blisters and cuts... Handsewing is not easy. Would I do it again? Absolutely - and I plan to make another rig for a S&W Model 645 pistol sometime before the end of the month. Right now, I'm just gathering ideas, and will make the pattern right before I start working on the rig.
Louis Awerbuck (named as one of two modern day "pistol masters" by Jeff Cooper before he passed away) once picked up a Fobus holster when we were on break during a class... He looked at us and said (in his distinct South African accent) "They are ugly as hell and are cheaply made, but they damn sure work!"
So... A large part of your decision is purely personal... Looks, costs, etc. Holsters are like women: Some look very good, but can make you very unhappy once you try to live with them - and can cost you a bunch of money if you've made the wrong decision. The ugly ones may, or may not make you happy, but if you made a mistake, you don't feel so bad about ditching an ugly one and losing the investment!
Regards,
Mike