Just about all the ones I would've said are taken. I particularly have love for Schwarber's blast in Pittsburgh, one of very few times I yelled "OH MY GOD" like as the ball was hit. Javy's parking one off Lackey (already posted) on a pitch that was off the plate outside was a great 'HOLY horsefeathers' moment. Russell's Game 6 slam always gives me the fuzzies because it reminds me of how the secondary ticket market for Game 7 absolutely exploded over the next hour and I knew immediately that Cubs fans were going to take over Cleveland the next day. Montero's slam will always be kind of underrated - I think our collective psyche (mine, certainly) was shaken after giving up the lead in the top of the inning and that was another "nope, we're awesome, get ready" moment from the playoffs. While on the subject, Rizzo and Russell both breaking out of slumps with big dongs in Game 4 of that series, in LA, are also in that category. I still haven't completely wrapped my head around the fact that of the 3 Cubs walk-off slams in my lifetime (shouts to Jason Heyward), I was in the bleachers for 2 of them. Bote's was already posted, and I was also there for Soriano's in 2009.
One hipster choice I have is a random spring training homer Javy hit in 2014 that went like 420 feet to nearly dead center, and I just remember seeing how hard he hit it and just bursting out laughing at how much power he had.