Been doing some reading about AIWB, I am wanting to make the change. I have some time before I can, I have some weight to lose before I can really start.

I do keep reading that there are good and bad Holsters, and have read that this holster is a good one where that one is not.

What makes a good AIWB holster? And what point  would you add the claw or a pad?

I think a lot of us like the ability to move it / slide it to the side in certain circumstances.  Some holster makes put loops or clips out at the far edges, and this design really limits the amount one can slide the holster.

The ability to slide it to the side (as much as pants/trousers belt loops allow) for vehicle trips is nice, as is it in other situations.

Probably the most important is: leather.  Leather is very, very comfortable to have against the skin, and I'm a strong proponent of leather loops instead of the common metal clip. Now the Sheriff of Bagdad Condom design has a clip for a reason, but that reason is the ability to use it on molle gear - and I don't ever have the need for unmounting a IWB holster and then mounting it on my chest.  
Leather loops have proven to me to be easy to slide (two close ones - not two wide-apart ones), and I've never once chaffed my arm or wrist against leather loops like I have with metal clips of clip-on holsters.

Edit: Don't put yourself behind the eight-ball by insisting on appendix-carrying a heavier firearm; I've seen people do it with Glock 19's, but only for a short while, and even they admit that they skip carrying sometimes.  I'm done it for seven years - just about every day that I leave the house (except for directly to work and back, at which time the holstered firearm is beside me) - with a S&W 642, and am just now switching over to the Shield 9mm.  Like all the lessons I've learned with holsters before, the new Shield holster will be leather, and will have leather straps.

Edit #2: since I just had this conversation yesterday, a buddy with a bit of a gut actually sent a new IWB holster back to the high-end holster maker he bought it from who re-did the holster to have the weapon sit lower.  My buddy, who is the best gunman I personally know, made the valid point that with a bit of a gut, the lower the handgun's grip sits, the easier it is to App carry for wider guys.  (keep in mind that for app carry, you don't want the FBI cant / tilted holster designs).

Will be carrying a G43 and possibly a G19 size.

I'm not overly wide, but more so in front . I know I don't need to be completely flat belly, but when I tried it last time, still with a belly, but with a RCS Vanguard on a G26, it was ok standing but unbearable sitting. My pants do sit a bit lower, more on the hips than the waist, which may be part of the issue as well

Small guns like the 43 don't carry well AIWB because most of the weight is above the belt. Larger guns like the 19 carry much better in the proper holster (RCS Eidolon).

The benefit of AIWB is that you can carry much larger guns quite easily. My daily carry is a Roland Special (34 length with an X300). i could barely get away with carrying a stock 19 when i was just carrying strong side.

Last couple months I've been carrying a full-sized 1911 in a jmcustom aiwb 2.0 holster with claw and extra tuck. Absolutely perfect.

Before that I carried a beretta m9a1 compact in a M13 tactical aiwb and it is great. No complaints. I still carry it almost half the time.

I also often carry a g19 in a jmcustom aiwb 2.0 with claw. It doesn't have the extra truck and I find the back of the slide is not tucked into me as much as possible. I think I'm going to duct tape a piece of foam to help.

I've used the original vanguard and vg2. They're ok but the holsters above work the best Imo and I've used a bunch.

I think the key is wearing your belt higher. I understand you're trying to loose weight which might help with that.

A good belt helps alot too.

When carrying AIWB I find it more comfortable to pull my pants up higher when I sit down.  I otherwise wear my pants the same as you.

Other than the leverage point of the pad, does it aid in any comfort below the belt? Instead of kydex poking, is the pad being softer aid here?

Adjustability (Make sure you can adjust it in every direction possible, not just a FOMI clip that can be placed at 10 degrees)
Modularity (Make sure that the holster can utilize multiple types of hardware)
Utilizes a claw (The leverage point that rotates the butt of the gun towards your body)

That's about it. The "wedge" a.k.a. foam pad (or rubber for the Raven Eidolon) helps, but isn't necessary for smaller guns.

I carry a Glock 19 with the RCS Eidolon and I love it. Had it for about 2 months and carry everyday all day. I am not a small guy either (6'0 and 225) the only bad part of AIWB is when I carry with Cargo shorts. The gun tends to sag a little bit and push more into my pelvis.

You're right and wrong.

Most small frame holsters are junk.

If you get a good holster, you can have most of the gun below the belt, allow for a full firing grip, and conceal very well. It matters more to support the slide weight, rather than the grip, like most cheap kydex holsters do.

I see exactly what you're saying, and it makes perfect sense. For these smaller guns, it looks like they are grabbing the trigger guard and the rest just sits there, whereas on the bigger guns, they are doing a full support all the way around and still grabbing the trigger guard. That way supports the weight better versus just right around the trigger guard and grip.

Also, it look like you were carrying in the picture closer to the 2 to 2:30 side, with having the leg Bend up are your pants just riding higher or is it canted to move with a natural movement of your leg?

That was just for the picture. I typically carry it at 1 o'clock, but even at 2-3 o'clock there are no issues with bending your leg.

The holster is canted to allow for a full firing grip. If the holster were not canted, the loop would need to be located further towards the muzzle to allow for a full firing grip. This would cause the unwanted condition where more of the gun is over the belt line.

I made the holsters pictured. I went through about three revisions before I was happy with the final design. I've now been carrying it like that for over a year without issue.