Opening confession: I've never had Tim Hortons or DD's. That firmly established, I can now climb atop the sopabox I carry for just such occasions and tell you that they all make lousy coffee. But here's the thing: if you like a double shot pumpkin spiced half and half semi skimmed accino, more power to you. Go for it. Starbucks have made a great business marketing coffee based drinks (that I don't think are coffee at all) and do this by creating a consistent base taste by over-roasting and destroying all the individuality you can get from a bean, then masking that burnt taste (or building on it) with milk, syrups, chocolate sprinkles and god knows what else.
I like to use an analogy to scotch. If you like a Bells and coke, you enjoy it. But if you so much as add ice to an 18 year old Edradour ... there's a special place in hell reserved for you. Coffee is exactly the same. Get a city roast yirgacheffe as soon as they're available and you will taste flavours in that drink that you never realised could exist in coffee. The aftertaste is pure blueberries. I've had coffees that taste of mint. strawberries. vanilla, chocolate, rum soaked raisins ... the list goes on. All these flavours come through from a simple "pourover" brew in the same way that you can taste peat, sea-spray, heather or any number of other things in scotch. It might be that you think the taste of strawberries and vanilla in coffee is really off-putting - in that case, avoid an Ethiopian Guji. In the same way, you might not like the salt/peat heavy scotch - so avoid an Islay.
If you're open minded and interested in the different flavours that you can get from different beans, try that hippy coffee shop and just ask the guy at the counter to surprise you with what he thinks is the best drink they have.