I've mostly tried them all, here's what I have to say, and trying not to be bias:
Ralph Lauren - Shirts i've owned 7 years ago become sentimental and still a great fit and look like they were made to be worn by me- although their collars annoy me sometimes - with careful care you can make the collars last, but when they go, they go.
Gant/Rugger - adding this here because they make quite nice Polos, although a bit pricey, they fit well and are pretty good quality. The styles they offer are unique and not as tacky as Lacoste's
Brooks Brother - several years ago they were pretty bad, but recently have been improved
Lacoste - the original and best 'Tennis' polo, although I have disdain towards them for their shrinkage and durability over time, surprised others hav emet better success. Otherwise Lacoste is great, and a sentiment and reminder of Rene Lacoste AKA 'the Crocodile'
Fred Perry - hit and miss, though accurate depiction apart from Lacoste of the 'perfect' tennis polo
Penguin - sort of a cult following brand from what I've seen. Nothing really inherently wrong with Penguin apart from what any other Polo goes through - at this point its merely preference of fit and style
Canterbury - don't know enough but others do it better, no reason to come here or consider their polos
Burberry - sad attempt at trying to plaster their logo, Burberry shouldn't have to do this
Abercrombie and Fitch - Highschooler's dream, wannabe's - but certainly not 'trash'