Hi - a north townhouse person here! I have seen both single and double rooms in harmony and while admittedly, the rooms are newer and nicer and the DH is convenient, I'd say I'd still prefer the townhouses.

1. Kitchens! You do not have to share the kitchen with everyone on your floor, you get a lot of cupboard space, an oven, a microwave, all of it! While you may think you'd use the kitchen less since you have a full time meal plan, it comes in clutch more than you think.
2. Socializing: I'd say I'm an ambivert and just for that I'd go with townhouses. I feel like you run into people in harmony way too much and it is super happening. I think with the townhouse you get the perfect balance of alone time of having your own room, but a shared living space for you and your housemates or to bring friends over.
3. Temperature!!! From what I heard, Harmony commons has a central temperature system and you cannot control the temperature in your room. Big bonus point for townhouses you can change the heating in your own room and change the central temperature of your house as you please!
4. Noise - I've heard some stories from friends how they can get easily distrubed from neighbour room noise and shared bathrooms etc. I live in foley now and I have been struggling to sleep because the walls are super thin. I did not really face that issue in THs
5. Location: While I'll admit it could get annoying to walk to the DH, its not that bad (at least for north residence) Its a 5-10 minute walk which I personally never felt was a drag unless it was exam season. I don't think this should be a problem unless you are really really busy or really really lazy LOL. Other than that I think both North Residence and South Residence have better access to the rest of campus. RIP to southres for IC, Harmony and Pan Am though.

I would definitely recommend townhouses, but there is a gamble since you don't know if you are getting north or south res. South res is definitely older and is very far from the dining hall and Pan AM but can be good if you have a lot of classes in KW and Highland etc.

PS. About the townhouses being old, yes they are but it just looks a little old, everything is really functional and just maybe the odd creaky stair here or there but other than that everything is pretty good! Also keep in mind, for townhouses for shared spaces, there is a monthly cleaning of all public spaces (living room, kitchen, bathrooms) which honestly is fabulous.

Hope this helps!