T-mount propellers are those that are based on a 1.5mm diameter centre shaft secured by a 2mm screw either side. They have been the only mounting option for 2-2.5 inch props but are now becoming more popular for 3" due to the weight they save over a 5mm single shaft prop mount. There are only 4 different types of t-mount 3" prop currently available so I've compared them all plus the new HQ 2 blade which is due for imminent release plus a darkhorse prop in a smaller size to make up the numbers. Please note this is a subjective comparison based on my opinion but my help as a startpoint for your decision. This is based on real world feel, light time and bitter experience with motors I've burnt out.
Emax Avan 3 inch tri-blade
This is the first modern design 3 inch prop designed for a t-mount which was released with the 3" Babyhawk R (reviewed here).
HQ 3x3x3 v1s tri-blade
HQ props have the newest 3" t-mount prop design at present. This has been chosen as the stock propeller for the Full Speed Leader 3 (initial review here and flights here)
Gemfan 3035 triblade
This is quite an old prop and can be hard to find but is still suprisingly relevant.
Gemfan 3025 bi-blade
This is the original 3" t-mount prop and so can be found for sale in weird and wonderful places
HQ 3x3x2 v1s bi-blade
Just released at the time of writing: as per the 3x3x3 above but bi-blade rather than triblade. Disclaimer: I have not tested yet and below information based on assumptions from comparing bi-blades and tri-blades in general. Will update once mine arrive and I've tested.
Dark horse to consider...
Gemfan 2540 flash triblade
Yes this is a 2.5" prop but objectively it is so good it is worth considering downsizing. You can find an earlier review I did on these here and a review on the Skystars Bolt X120 which uses these on 4s here
Please note the King Kong 2840 propeller was not included here because I found the Gemfan 2540 superior in every way. Also I have not include the Rotor X 3044 because it is difficult to source where I am based. The feedback that I have had is that it is more aggressive in pitch than any of the above props and probably only suitable for for stator sizes 13xx and up.
My first impression here was not great - I was not used to the notchiness or seemingly noisy bearings and I had heard bad things about the wires. This was largely solved during build and first few flights - the bearings settled down, the notchiness was the sign of strong magnets and the wires were manageable although still difficult to solder compared to multicore silicon wires.
Flying on a 2 inch quad
These firstly went on a 2 inch quad here but it felt like it was working to hard just to stay hovering. It was super quick on punch outs but general flying was not enjoyable. My thoughs after some time that the motors were too much for the props (King Kong 1935 or Gemfan 2035) so decided to try a larger build
Flying on a 2.8inch quad
I transplanted the running gear over to a FD120 frame which is more commonly know from the excellent PNP leader 120 on this build here. The improvement was immediately noticeable - hovering at a lower idle and flight with a lot more control and resolution, really shining with the larger 2.8 inch King Kong 2840 props. It is fast on 2s and mental on 3s. Although I am a big fan of lightweight for micro builds especially, this build could manage the weight a lot better... batteries ranging in weight from 48g 2s 950mah to 18g 2s 300mah was not as different as you would think.
Final thoughts and recommendations
Firstly I would encourage soft mounting for absolutely all brushless motors. Here is a link for 11xx series motor soft mounts on thingiverse, I got 12 printed for less than $US3 on 3dhubs. Secondly I think these are too much for a 2 inch prop. You may have a different experience but this is mine. I thought a 2.5-2.8 inch prop is right at the sweet spot or 3 inch for a 2 blade like the gemfan 3025. I find the motors themselves well built and very powerful. They have the ability to draw a lot of current, especially on 3s. Because of this I would recommend these 7500kv version for 2s although they are certainly capable of 3s without overheating - I do actually run 3s more often than 2 on this quad. Having had my time again I would have gone 6500kv for mostly 3s as they are more efficient: less current, more torque, longer run time with a small hit on top speed. If I was building the same quad tomorrow from scratch in 2.5 inch and 2s, I would by these again. For 2 inch I would rather go for a lighter build based around 1103 motors.