The last thing the OP should be worried about is how others feel about the kit lens.. the question should be - are you, the OP, generally satisfied with the results of your kit lens ? If so, leave it alone till you are not. As far as ratings are concerned, if you ask a hundred people, you will get 100 diverse opinions as to which lens you should get and why... Buy based upon your needs and your observations -- based upon your current equipment.. Do you need a faster lens? Do you need a longer or wider lens? Narrower DOF ? What are you trying to accomplish that you can't with your current gear ? If money is tight- learn how to use your equipment ot overcome its shortcomings- even if you go back 20 years- the equipment in use was far worse than the worst equipment one gets today in a kit!.. As far as the tamron- it may be praised by some- and cursed by others.. It's a matter of what is important to the person behind the camera. My understanding is that the AF speeds of the Tamron lacks compared to the competition. The VC version is noted for lower IQ. The Sigma OS version focuses faster, and is well built and is quite sharp.. The Canon version is well respected - now- but had problems early on & of course- is quite pricey. In the end, don't upgrade your equipment until you become dissatisfied with some aspect of it or till you feel the need for something more/less/different. Reality is that there is a fair number of people who upgrade their lenses, incorrectly, because they don't know what they want and why- and are usually disappointed in the end result.
That said- have you ever heard of the expression about burying your head in the sand ? Lenses are kind of like this. If all of your lenses are about the same quality- and you never try a "better" lens, you probably won't know what better is like. In the end, your kit lens is probably fine if you stop it down to say f/8 for maximum sharpness.. Maybe decent even wide open. However, at f/8, most lenses are very similar.. BTW: Better to one person may mean a wider aperture like f/2.8.. To another, a wider lens might be better. . to another- a longer lens will be better. Everyone's concept of better is different for each..
EOS 5D III, EOS 7D,EOS Rebel T4i, Canon 70-200 f/2.8 IS II, Canon 24-105L, Canon 18-135 IS STM, 1.4x TC III, 2.0x TC III, Σ 50mm f/1.4, Σ 17-50 OS, Σ 70-200 OS, Σ 50-500 OS, Σ 1.4x TC, Σ 2.0x TC, 580EXII(3), Canon SX-40, Canon S100
Fond memories: Rebel T1i, Canon 18-55 IS, Canon 55-250 IS, 18-135 IS (Given to a good home)...