Not considering resale values, it's going to depend on your use of the garage.
Using it to store some household goods? Pro to the attached for convienence.
Going to end up heating it? Pro to the attached as the gas line would be shorter aka cheaper (also less exterior exposure).
Want to work inside of it and/or make noise? Pro to the laned/detached garage.
Want more backyard than front yard? Pro to the attached (in most cases).
Want more (or even some) street parking? Pro to the laned/detached.
I personally went with the laned/detached garage as I use it as a shop. If I didn't, I'd go with an attached as I always found it more convienent (forgetting a tool in the garage is a PITA in the winter).
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