to the OP, go for it. Subaru continues to have some of the best reliability ratings around. The thing that drags Subarure reliability ratings down sometimes, is the BRZ, WRX and STI. Not that these aren't reliable cars, but that they are very popular with tuners. And once you get some amateur poking around under the hood trying to squeeze every possible bit of power from an engine, then going out and driving it hard. Well, things fail.
One poster here has criticized Subaru for having interference engines with timing belts. He is a little out of date. Subaru started putting a timing chain in at least the 2.5 back in '12. Besides, I spend a lot of time on an Outback discussion board. Been there for almost two years, and I have yet to hear anyone who has damaged an engine from a failed timing belt.
Some have criticized the Legacy because it only comes with a CVT. In my opinion, these critics are a little outdated, but at the least it is a matter of preference. From all the reviews that I've read, the CVT being used in the '15 Legacy/Outback is one of the best driving CVT designs out there. Many have commented that it would be difficult for all but the most trained driver to be able to tell between the CVT and a traditional AT.
I see you live in NY. You would be very pleased with the security that the Subaru AWD system would give you. Spend a little of the extra money you would have spent on a TLX and put it into a quality set of studless snow tires.
I can't speak as to how hard the plugs are to change. I haven't done that on my car yet. Although, I have seen do-it-yourself videos made by other Subaru owners, and they say it just takes a few knacks. They can't be any harder than getting the back plugs out of my 3400 V6 in my Alero. The rest of the maintenance is pretty easy. Differential fluid change is a breeze. Oil & filter change on the 2.5 is super easy. Easiest filter change of any car I have ever worked on. Air filter is as a five minute job, but only because I'm a little anal about cleaning out all the debris in the filter box. Cabin filter is about a two minute job. At least for general maintenance, I would much rather work on my Outback than on the Camry I used to drive. Although I haven't done it yet, drive belt appears to be super easy too. Once again, it looks like it will be easier than many other cars I have owned.
You may hear some negative comments about head gasket repairs on Subaru engines. this is a problem that Subaru had on earlier models, I believe in the 2006 - 2009 models. I haven't seen any complaints in 2010 and later models. Interestingly enough most those I know who have had head gasket issues, love their Subaru enough that they get the repair done, and then continue driving their Subaru for many more years.
As far as engine, I have been very happy with the 2.5, but then I'm a little more concerned with economy, than I am with power. But if you still want the power, go for the 3.6. I know some of the auto critics say it doesn't have enough power, but most owners I know have been very happy with the 3.6 power. Remember what the Legacy is made to compete against. Cars like the Camry and Accord, where the 3.6 has very similar power.
Go drive one. I've got a few invitations from Subaru and my local Subaru dealership, to drive a Legacy. I know they are anxious to show it off.