I need some suggestions guys.

The velcro on my Wilderness Tactical instructors belt is getting a bit thin after about five years. I am going to send it back to them to get the velcro replaced, but I also want to get a new belt.

I am looking for a belt with the lowest profile buckle I can find. I carry AIWB and usually have the buckle around the 2 or 11 o'clock position to minimize bulk at the 12 o'clock position.

I also like a very stiff belt. I use the Wilderness Tactical Instructor 5 stich with CSM which has a layer of polymer sewed into it. After five years you still cannot squeeze the belt at all and get it to flex. I had a regular Instructor belt, 5.11 I believe, that after a couple years you could easily squeeze the belt together, I don't want that.

So: very rigid and low profile buckle. Any suggestions?

Though not really completely low profile in size the Frequent Flyer belt has two rings that the belt goes through in order to hold it without any holes in the belt.  
Being round the rings shouldn't irritate the tummy much bending over.  Being synthetic they won't react to metal detectors hence the name.

The most comfortable wide belt in hot weather is probably cotton webbing.
I have a cartridge belt made from cotton canvas and though a few inches wide it was still comfortable in high heat in summer.

I carry a CZ P-01 in a Stealth Gear AIWB holster with a Beltman leather belt with the stiffener sewn in.
The holster fits in right up to the buckle perfectly for me.

I still use my 5 stitch for work but the velcro is pretty dead and it's starting to sag after at least 7 years. It was an OK belt but I like the Beltman better.

I have a frequent flyer with csm stiffener also. Great belt. Still wish I could find something less noticeable as far as the buckle.

I have a Beltman belt.....somewhere. Not really a fan of leather. And they really suck for my application.

I don't think you could wear out a Wilderness belt with csm. Mine is about 5 years old, the velcro is about gone, but it's as stiff as it was new. I think they will replace the velcro for $10, guess I'll find out in the next few days.

I use a GI type web belt. I think it was made by 511 tactical or some company.
It's very sturdy and doesn't have a stiffener.

I think width is 1.75. Works well for CCW.

Another vote for beltman

Ares gear Aegis belt.  Leather is not all that good they wear out, stretch, and eventually sag.  I have gone through lots of belts over the years leather, leather/kydex Comp-Tac, Wilderness, and a few others none last more than 2 years.  Working on year 3 with my Aegis and it has not sagged or stretched.  Also the buckle is amazing and allows me to quickly just tension on my waste.

Wow. You must have actually understood what I was asking about.

Thanks for the heads up. Looked them up, read a few reviews, and just ordered one. Says about 4 weeks on their website. Clock starts now.

You will not be disappointed.  I have been through lots of disappointment over the years with belts actually had a leather one snap on me while I was out of town in a shopping mall.  I had to walk around holding my pants up till I could get to a store and buy a cheap belt to get me by.  Been nothing but 100% satisfied with my Ares gear belt.  I was one of those who doubted how good their belts were and bought other cheaper belts over the years because 100+ bones seemed a lot for a belt.  Had I just bought one to start I would have been able to buy 3 or 4 of them.  You do not even want to know how much money I have wasted on holsters over the years.

I'm with you. About once a year I move my extra holsters on the EE. Last time I bought a P30L with the proceeds.

I give them away to friends so they can try them out and see how crappy they are and then they come back to me and ask what actually works.

My 5 stich wilderness has been a good belt and so has my Beltman but I am pretty intrigued by the Ares.
I usually wear nice jeans and tucked collar shirt so my leather Beltman gets used a lot. Problem is like most one day it fits the next it doesn't.
  The Wilderness is a bit to tactical so the Ares looks solid for a everyday belt.   I had honestly started thinking about a law enforcement inner belt with just velcro.