I love both games for very different reasons.
The Last of Us
Highlights:
Well Presented Story - The tone and consistency throughout the entire story of The Last of Us is largely unparalleled. Is it the greatest story in gaming? Probably not. But it's certainly among the most well presented stories in gaming. And there are a couple of legitimately great twists that are both great and play off of expected video game tropes without being obvious about it.
Under Appreciated Multiplayer - If you're into online MP gaming, then TLoU is a real treat. This mode largely goes unloved because the single player campaign hogged all of the spotlight after release. It's one of the few MP experiences that doesn't simply feel 'tacked-on' to a great single player experience for the sake of a bullet-point on the back of the packaging.
Lowlights:
Obnoxious/Distracting/Immersion-breaking AI companions - AI partners often run in front of the playable character - only to actively run into enemies or just do silly things that ultimately take you out of the moment. While these AI companions can't actually cause the enemies to see or sense you, it's just kind of strange to see them run into an enemy only for the enemy to not react. Additionally, there were a couple of moments where an AI companion ran into my FOV and I shot at them instinctively - only to then attract a clicker who proceeded to kill me. Normally, it's not a big deal - but it happened a couple of times for me.
Fairly typical 3rd Person Stealth Gameplay - As with the first Bioshock game, I had heard so much universal praise that I, for whatever reason, expected the gameplay to really stand out. TLoU's gameplay really is done well, but it's just not that special or unique.
Far Cry 4
Highlights:
Large Open World - The world of Far Cry 4 is even bigger than the world in FC3 - and thus, there's even more to do in FC4. If you're into collecting stuff in open world games, this game will keep you busy for quite a while. Even if you're not, the non-collectibles, non-campaign content is still substantial and will keep you busy for a while.
Co-Op - While TLoU has some MP content, it's not the same as Co-Oping through parts of the main game with a friend. As someone who doesn't really game online with people, I found Co-Op to be extremely fun with a buddy.
Level/Content Creator - Even the Console versions of FC4 (at least PS4/XOne) comes packaged with a surprisingly deep level/mission creator. Even better, players can upload their content and allow others to download and play it. This means that after you're completely done with the Campaign and side-mission stuff, you can always open into a custom made level/mission, save your favorite ones - or simply choose to play a random custom level. Of course, the best way to utilize this is to go to the 'Highest Ranked' and 'Most Downloaded' sections and save the best ones.
Lowlights:
Meh Overall Plot - It's Far Cry, you don't actually play it for the plot, do you? The story is presented in a compelling enough way, but yeah... try not to think too much on it or else it might make little to no sense.
Not enough newness to really 'Wow!' those who played FC3 - As someone who played and loved FC3, I was fine with FC4 being 'more of the same'. However, I can see why some would not like this considering the main entries of FC have always seen some substantial differences. Additionally, with this being Ubisoft, I understand the concern that they'll just regurgitate the same formula forever now that they found one that worked in FC3. On the plus side, they've done away with those nonsensical encounters with the main bad guys from FC3. Instead, the narrative justifies these more intimate encounters with the main baddies... instead of a contrived QTE encounter in a darkened area in which the player is magically transported out of after finishing the QTE.
Ultimately - I say get Far Cry 4. It will last you longer - and TLoU is likely (continue) to drop in price while you go through FC4. You'll likely find TLoU for $20-$25 in a month or 2 if you can't find it at that price right now.