Bahadur,
I cannot to speak to the quality of Sidearmor, I have no experience with their holsters, but they do have an excellent reputation.
I currently own 4 Blade Tech IWB holsters and I have tried the Blade Tech paddle holster. The paddle holster did not conceal well for me, but it was very well made, good fit and finish and good workmanship. The other Blade Tech IWB holsters are very well made, with adjustable holster tension. The Blade Tech holsters appear to be very durable, I shot a combat course with about 1,200 rounds in two days. There were more presentations from the holster than I can remember and the course involved a lot of active movement including prone shooting and rolling over while firing. This can be tough on an empty holster, and several broke, but my Blade Tech IWB did very well. The Blade Tech holsters are very smooth and can be a very fast holster. I am very impressed with the Blade Tech holsters.
I am also impressed with Blade Techs customer service, when I received the paddle holster and decided it did not conceal well for me, Blade Tech quickly exchanged the item for an IWB holster. I was very pleased with the speed and efficiency of their service.
I only have one Comp-Tac hoster it is the C-T.A.C. The holster is very well made and is very concealable. This is the only tuck-able holster I have any experience with, but having said that I am very impressed with how truly concealable this holster is. I have only shot a one day course with this holster, and I have only owned it for about 6 months so I am not sure how durable it will be. So far I have no complaints. The Comp-Tac is more comfortable to wear than my Blade Tech holsters are. The Comp-Tac design is also much thinner overall. My Kahr K-9 really disappears in this holster. I have a slower draw with Comp-Tac than I do with my Blade Tec.
Having, said the above, in my opinion leather is more comfortable that kydex, but the comfort is offset by my environment. I live in a hot humid area and I sweat so I choose the protection of Kydex over the comfort of leather. If you are looking for the ultimate in comfort take a look at Milt Sparks. I think Kramer Leather is a good compromise between comfort and durability.
If you have any specific questions please feel free to ask. I will be happy to attempt to help if I can.
Good luck with your holster search.
Charles