all charge same prices, but some offer better free gifts than others.best idea is to pay cash -euros- if you can, but if you are using a credit card check total price before completing transaction as some add up to 3% for using card and some will convert to sterling and charge you in sterling.
as ever it is buyer beware, but if you check total deal you should be ok.
we used tabac near church in main shopping drag last year, but i feel better deal is had just of main shopping street near station turn off-cant remember name.
further warning, -some shops sell cigs in packets of 19 and so they can appear cheaper -and they sometimes make "mistakes" when you buy a large quantity and you get some cartons of 19's instead of the 20's you paid for(got that t-shirt ) -so be aware.

HI JM ,Thankyou for your info. I will be very carefull and pay cash .God bless low cost fares , maxie